WO2025012653A1

WO2025012653A1 - Vehicular glazing

Info

Publication number: WO2025012653A1
Application number: PCT/GB2024/051816
Authority: WO
Inventors: Anna Louise COLLEY; Xavier ARNAUD; Mitsuhiro Kawazu; Ayse ERSOY ALLISON; Yoko Watanabe
Original assignee: Pilkington Group Limited
Priority date: 2023-07-11
Filing date: 2024-07-11
Publication date: 2025-01-16

Abstract

The present invention relates to vehicular glazings comprising an outermost layer comprising from 0.5 to 20 atomic % cerium based on all components and to processes for producing such vehicular glazings including a step of sputtering a sputtering target comprising cerium oxide to provide a layer comprising cerium oxide directly or indirectly on a first surface, the invention also relates to the use of a layer comprising cerium oxide as a durable and long-lived hydrophobic surface on vehicular glazings, and vehicles comprising vehicular glazings comprising an outermost layer comprising from 0.5 to 20 atomic % cerium based on all components.

Description

Vehicular Glazing

The present invention relates to vehicular glazings, in particular vehicular glazings with a durable and long-lived hydrophobic surface, to processes for producing such vehicular glazings, and to the use of a layer comprising cerium oxide as a durable and long-lived hydrophobic surface on a vehicular glazing.

It is desirable that water is removed easily from vehicular glazings so that light transmission through the glazing to occupants or sensors is not impaired. A glass surface is typically hydrophilic, causing water to "sheet" on the surface. This water layer is difficult to remove, and may impair occupant or machine vision through the glazing. To reduce water sheeting, the glazing surface may be made more hydrophobic. The use of a hydrophobic surface prevents water sheeting, and may cause water to bead into droplets, which may be removed more easily - therefore a hydrophobic surface is associated with improved visual acuity through the glazing.

It is also desirable to reduce the weight of existing vehicles, especially electric vehicles, to improve vehicle fuel efficiency and range.

Water droplets on a hydrophobic surface may be more easily removed by wiper blades. This allows the use of light-weight wiper blades and less-powerful low-weight wiper motors, reducing the both the energy consumption of the motor and total vehicle weight, allowing for an increase in fuel efficiency and range.

Furthermore, the use of hydrophobic coatings may allow wipers to be dispensed with, reducing the weight of the vehicle by removing the need for wipers, wiper motors, and associated wiring. Such weight saving is particularly desirable, for example in electric vehicles such as electric automobiles.

In addition, compared to a hydrophilic surface, water droplets are more easily removed by air resistance from glazings which are not wiped by wiper blades, such as sidelights, because less energy is required to remove water droplets from the surface.

Coatings on substrates, especially glass substrates, may be used to modify the properties of the substrate. A number of methods may be used to deposit coatings upon glass substrates, such as liquid based methods including spin coating, dip coating, and spray coating, as well as chemical vapour deposition (CVD) and physical vapour deposition (PVD). Physical vapour deposition is also known as sputtering. In the past coatings have been used to render the glazing surfaces hydrophobic with a hydrophobic coating using, for example, sol gel formulations of hybrid organic-inorganic precursors, modified silanes with sol gel additives, or modified silanes which chemically cross-link after surface treatment. Other products include reactive silicone fluids to coat the surface with an easy-to-clean polymeric coating or polymeric resins to provide a low maintenance, non-stick surface.

However, many of these previous hydrophobic coatings are not sufficiently durable to adhere to the glazing for the lifetime of the vehicle or glazing, and overtime are dispersed into the environment. This is of particular concern when the coating includes substances that are detrimental to the environment. One class of substances that is considered to be detrimental to the environment is per- and polyfluoroalkyl substances (PFAS). Certain PFAS are undesirable, due to their classification as persistent organic pollutants (POPs), which are organic substances that persist in the environment and accumulate in living organisms, causing harm. Other PFAS are not currently banned, but are undesirable to consumers. Therefore, it is desirable to provide hydrophobic coatings that do not allow PFAS to enter the environment. In addition, the short lifetime of prior hydrophobic coatings, caused by their low durability, means that they must be repeatedly applied in a time consuming manner, and are repeatedly released into the environment, further increasing their potential environmental damage.

Therefore, it is an aim of the present invention to address the problems with known products or methods and to produce vehicular glazings that have long-lived low water-surface adhesion, and are less likely to introduce harmful substances into the environment.

In a first aspect, the present invention provides a vehicular glazing with a durable and long-lived hydrophobic surface comprising: a glass substrate with a first surface and a second surface; and a layer comprising cerium oxide directly or indirectly on the first surface, wherein: the layer comprising cerium oxide is the outermost layer on the first surface; and the layer comprising cerium oxide comprises from 0.5 to 20 atomic % cerium based on all components. The inventors have found that the outermost layer comprising cerium oxide as described in the present invention provides a coating that provides excellent hydrophobicity performance, therefore providing vehicular glazings with low water-surface adhesion. In addition, the outermost layer comprising cerium oxide is much more durable than prior hydrophobic coatings, therefore providing long-lasting hydrophobicity, and also is less likely to be dispersed into the environment. Furthermore, the layer comprising cerium oxide does not comprise PFAS, and the excellent hydrophobicity performance is obtained without the use of per- or polyfluoroalkyl substances, and therefore is less likely to cause environmental harm.

According to the present invention, a vehicular glazing has a durable surface if the surface is durable to the extent that the surface: achieves a score of 5 or less, preferably 3 or less, more preferably 0 when submitted to an oil-rub 50 test as detailed herein; and/or achieves a score of 5 or less, preferably 3 or less, more preferably 0 when submitted to a mini-brush test as detailed herein; and/or passes a dry abrasion mar resistance test according to ASTM D6037.

According to the present invention, a vehicular glazing has a long-lived hydrophobic surface if the surface achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55°, after a test selected from the list consisting of: oilrub 50 as detailed herein, oil-rub 500 as detailed herein, minibrush as detailed herein, or dry abrasion mar resistance according to ASTM D6037.

Preferably, the first surface does not comprise a layer comprising per- or polyfluoroalkyl substances.

Preferably, the glass substrate is a soda-lime silica glass substrate. Alternatively, other glass compositions may be used, as borosilicate, aluminosilicate, boroaluminosilicate.

The layer comprising cerium oxide is the outermost layer on the first surface. When the layer comprising cerium oxide is the outermost layer on the first surface the layer comprising cerium oxide is directly exposed to the vehicular glazing's environment.

The layer comprising cerium oxide is on the first surface, in that the first surface comprises the layer comprising cerium oxide. The first surface may be substantially entirely coated with the layer comprising cerium oxide. In this case, the entire vehicular glazing is provided with the coating, and the hydrophobic effect is provided to the entire glazing. Where the vehicular glazing is a fixed vehicular glazing, such as an automotive windscreen, backlight or rooflight, it is desirable for that the entire vehicular glazing is provided with the coating, such that the first surface is substantially entirely coated with the layer comprising cerium oxide.

Where the vehicular glazing is provided with wipers, it may be desirable that the area swept by the wiper blades includes the layer comprising cerium oxide, to improve wiper efficiency. Alternatively, the area swept by wiper blades may not comprise the layer comprising cerium oxide, and other areas may comprise the layer comprising cerium oxide.

In some embodiments, the vehicular glazing is provided with a camera or sensor. It is particularly beneficial that where the vehicular glazing is provided with a camera or sensor that receives electromagnetic radiation, the area of the first surface that electromagnetic radiation must pass through to reach the camera or sensor, defined herein as the sensor area, is provided with the layer comprising cerium oxide.

Water droplets in the sensor area reduce the acuity of the camera or sensor, causing a deterioration in image quality and potentially misfunctioning of any automatic driver assistance systems associated with the camera or sensor. The layer comprising cerium oxide improves the hydrophobicity of the sensor area, reducing the energy required to remove water droplets and therefore reducing the number of water droplets which may be present in the sensor area which otherwise might cause a deterioration in camera or sensor acuity.

It is particularly preferred, when the sensor area is not within an area of the vehicular glazing that is swept by a wiper, that the sensor area is provided with the layer comprising cerium oxide, to allow the effective removal of water droplets by wind resistance alone.

In some embodiments the vehicular glazing is adapted such that the first surface comprising the layer comprising cerium oxide is disposed towards the exterior of the vehicle. This is particularly beneficial considering the hydrophobicity of the vehicle exterior. However, in other embodiments the vehicular glazing is adapted such that the first surface comprising the layer comprising cerium oxide is disposed towards the interior of the vehicle. This is particularly beneficial when a hydrophobic surface in the interior of the vehicle is desirable, such as multiple occupancy vehicles and public transport vehicles, as such a surface may be more easily cleaned. In addition, a hydrophobic surface on the interior surface of the glazing, such as that provided by the layer comprising cerium oxide, reduces the impact of condensation, as water droplets that condense on the interior surface are easily displaced by gravity alone. In some embodiments, the vehicular glazing comprises a layer comprising cerium oxide on the exterior surface and the interior surface.

Preferably, the layer comprising cerium oxide is homogenous in cerium. A layer comprising cerium oxide that is homogenous in cerium comprises cerium atoms which are dispersed to a homogenous extent across and through the coating layer. Preferably, the cerium atoms are within and constitute an amorphous or semi-amorphous coating layer applied to the first surface, such as that which is provided by sputtering. Preferably, the cerium atoms are not within nanoparticles, and preferably the layer comprising cerium oxide does not comprise particles and/or nanoparticles. A layer that is homogenous in cerium and does not contain particles and/or nanoparticles may be less likely to be abraded by a wiper blade, due to decreased surface roughness. In addition, certain nanoparticles may not be acceptable to consumers.

Advantageously, the vehicular glazing is corrosion resistant as indicated by a relatively low increase in haze after weathering. Weathering may be accelerated by high humidity, heat or hot/cold cycles and for testing purposes weathering may be simulated by maintaining the glass at an elevated temperature in high humidity for predetermined periods. Usually, the measured haze (using e.g. a haze meter) of the coated glass will be 25% or below, preferably 20% or below, more preferably 15% or below, even more preferably 10% and most preferably 5% or below after 50 days at 98% relative humidity and 60°C. Preferably, the corrosion-resistant coated glass substrate exhibits a haze increase of 55% or below, more preferably 35% or below and most preferably 24% or below after 50 days at 98% relative humidity and 60°C. The haze increase may be calculated by comparing the measured haze before and after weathering.

Usually, the layer comprising cerium oxide may have a thickness of 1 nm or higher, preferably 10 nm or higher, more preferably 20 nm or higher and most preferably 30 nm or higher. Coatings that are too thin may not be sufficiently durable or effective. It is preferred that the layer comprising cerium oxide has a thickness 500 nm or lower, preferably 250 nm or lower, more preferably 100 nm or lower and most preferably 50 nm or lower. Coatings that are too thick may be subject to cracking during a heat treatment or toughening process, and may be uneconomical to produce. Thus, preferably, the layer comprising cerium oxide has a thickness in the range 1 nm to 500 nm, preferably 5 to 250 nm, more preferably 10 to 100 nm. Such thicknesses are advantageous because they provide a good balance between corrosion protection, durability and economy of production.

The layer comprising cerium oxide will usually have a refractive index in the range 2.28 to 2.44.

In some embodiments it is preferred that the layer comprising cerium oxide is the only layer on the first surface. However, in alternative embodiments it is preferred that an underlayer is provided between the layer comprising cerium oxide and the first surface. Preferably, the underlayer comprises silicon oxide. Such an underlayer may improve the adhesion and durability of the layer comprising cerium oxide. Preferably, the underlayer comprising silicon oxide is directly on the first surface. This further improves adhesion and durability of coatings upon the substrate.

In one preferred embodiment the underlayer comprising silicon oxide is directly on the first surface, and the layer comprising cerium oxide is directly on the underlayer comprising silicon oxide. This arrangement of layers provides excellent adhesion and durability of coating layers in an efficient manner.

Preferably, the layer comprising cerium oxide comprises from 1 to 10 atomic % cerium based on all components, preferably from 2 to 8 atomic % cerium based on all components. Such a range is shown to provide excellent hydrophobicity.

Preferably, the layer comprising cerium oxide is substoichiometric in oxygen.

Preferably, the layer comprising cerium oxide further comprises titanium, preferably the layer comprising cerium oxide comprises from 50 to 95 atomic % titanium based on titanium and cerium, more preferably the layer comprising cerium oxide comprises from 70 to 90 atomic % titanium based on titanium and cerium, even more preferably the layer comprising cerium oxide comprises from 75 to 85 atomic % titanium based on titanium and cerium.

The inventors have found that a layer comprising cerium oxide and titanium, is a particularly effective corrosion-resistant cleanable coating with excellent durability. In addition, the inventors have found that such coatings may be readily deposited by sputtering. Preferably, when the layer comprising cerium oxide is a layer comprising cerium oxide and titanium, Ce_xTi_yOz, the atomic proportion of Ce based on Ce and Ti in the base layer, calculated as x/(x+y) is from 0.5 to 0.95, more preferably from 0.50 to 0.90, preferably from 0.55 to 0.85, more preferably from 0.60 to 0.80, yet more preferably from 0.62 to 0.67. The inventors have found that such ranges provide particularly durable and long-lived hydrophobic coatings.

Preferably, the layer comprising cerium oxide comprises less than 10 atomic % silicon based on all components, preferably the layer comprising cerium comprises less than 1 atomic % silicon based on all components, more preferably the layer comprising cerium is essentially free of silicon.

Preferably, the layer comprising cerium oxide comprises less than 10 atomic % aluminium based on all components, preferably the layer comprising cerium comprises less than 1 atomic % aluminium based on all components, more preferably the layer comprising cerium is essentially free of aluminium.

Preferably, the vehicular glazing exhibits a water contact angle of greater than 30°, preferably greater than 50°, even more preferably greater than 60°. Such water contact angles are associated with low water-surface adhesion. Therefore, according to the present specification a substrate is hydrophobic when it exhibits a water contact angle of greater than 30°, preferably greater than 50°, even more preferably greater than 60°, yet more preferably greater than 70°.

It is preferred that the vehicular glazing is a bent and/or strengthened vehicular glazing.

Vehicular glazings are often bent to conform to the aperture of the vehicle, and to increase the visual appeal of the glazing. The vehicular glazing may be bent, for example, by sag bending, press bending, cold bending.

Vehicular glazings that have undergone bending comprise a radius of curvature in at least one direction, preferably coated glass panes that have undergone bending comprise a radius of curvature in at least one direction of from 500 mm to 20000 mm, more preferably coated glass panes that have undergone thermal bending comprise a radius of curvature in at least one direction of from 1000 mm to 8000 mm. Vehicle glazings may be bent as known by the skilled person, and may preferably be bent as described in US10995029B2, EP3538498B1, US11434161B2, WO2018220394A1, W02020021273A1, for example.

Preferably, the vehicular glazing is a strengthened vehicular glazing, that is the vehicular glazing comprises at least one glass substrate which has been strengthened such that it is less susceptible to damage than an annealed glass substrate. A strengthened vehicular glazing is particularly advantageous because such strengthening enhance user safety. In some cases, the use of a strengthened vehicular glazing may be required to meet legislation. Strengthening may be accomplished by thermally or chemically toughening a glass substrate of the vehicular glazing.

In some embodiments the vehicular comprises at least one thermally toughened glass substrate. Glass substrates that have undergone thermal toughening are preferably at least four times as strong as annealed glass of a similar thickness. Preferably, the strengthened vehicular glazing comprises a thermally toughened glass substrate with a compressive stress on the surface of from 400 to 1500 kg/m², preferably 750 to 1500 kg/m².

In some embodiments, the vehicular glazing comprises at least one chemically toughened glass substrate.

The vehicular glazing may be a laminated vehicular glazing, wherein the glass substrate carrying the cerium oxide layer is adhered to a further glass substrate by an interlayer, often an interlayer comprising polyvinyl butyral (PVB). Laminated vehicular glazings are mandated for certain vehicular apertures, such as automotive windscreens. Where the vehicular glazing is a laminated vehicular glazing, the surface carrying the cerium oxide layer is not adjacent to the interlayer. The interlayer may comprise a single interlayer ply, or multiple interlayer plies. Interlayer plies may be provided to reduce sound transmission, or to decrease transmission of certain wavelengths of electromagnetic radiation, or to decrease or increase reflection of certain wavelengths of electromagnetic radiation. The laminated vehicular glazing may be a composite laminated vehicular glazing - such a vehicular glazing comprises a chemically toughened glass substrate and an annealed or thermally toughened glass substrate adhered together by an interlayer. A composite laminated vehicular glazing typically has a chemically toughened glass substrate which is thinner than the annealed or thermally toughened glass substrate. A laminated glazing may be provided as known to the person skilled in the art, preferably as described in WO2021038214A1, WO2021180954A1, US20080318028A1, US20010019759A1, for example.

The glazing may be adapted for installation in a vehicular aperture by addition of seals, or by encapsulation, or by the addition of fixings. The glazing may be adapted to hold fixings by having at least one hole (for example one hole, two holes, three holes, four holes or more than four holes) drilled through the substrate. If the substrate has at least one hole, drilled through the substrate, the substrate may be toughened after the hole(s) are drilled.

Vehicular glazings may be adapted for these apertures considering their visible light transparency, coating sequence sheet resistance, energy efficiency, shaping, etc. Typical vehicular glazings are provided with obscuration bands as is known to those in the art.

The glazing is preferably edge-worked, to reduce the risk of vehicle occupant injury where the vehicular glazing may be opened after installation, such as side-lights.

The vehicular glazing may be provided with a low-emissivity and/or infrared radiation reflection coating to improve the energy efficiency of the glazing. In some embodiments, the second surface comprises a low-emissivity and/or infrared radiation reflection coating. In some embodiments where the vehicular glazing is a laminated glazing, an additional substrate carries the a low- emissivity and/or infrared radiation reflection coating, such as a further glass sheet or interlayer.

According to a second aspect of the present invention, there is provided a process for producing a vehicular glazing according to the first aspect of the invention, the process comprising: providing a glass substrate with a first surface and a second surface; providing a sputtering target comprising cerium oxide; and sputtering the sputtering target comprising cerium to provide a layer comprising cerium oxide directly or indirectly on the first surface.

Preferably, the glass substrate is a soda-lime silica glass substrate. Alternatively, other glass compositions may be used, as borosilicate, aluminosilicate, boroaluminosilicate. Preferably, the sputtering target comprises titanium, preferably from 50 to 95 atomic % titanium based on titanium and cerium, more preferably the sputtering target comprises from 70 to 90 atomic % titanium based on titanium and cerium, even more preferably the sputtering target comprises from 75 to 85 atomic % titanium based on titanium and cerium. Inclusion of titanium in the sputtering target may improve the conductivity of the sputtering target, and thereby improve the rate of the sputtering process.

Preferably, the step of sputtering the sputtering target is carried out in atmosphere with less than 10 volume % oxygen, preferably less than 5 volume % oxygen, even more preferably less than 1 volume % oxygen. The skilled person may evaluate the sputtering atmosphere based on the flow rates of the sputtering atmosphere gases. Preferably, the step of sputtering the sputtering target is carried out in an atmosphere comprising a noble gas, preferably the noble gas is argon or krypton. Preferably, the sputtering atmosphere is greater than 50 volume % noble gas, preferably argon, even more preferably greater than 90 volume % noble gas, preferably argon.

When the sputtering step is carried out in an atmosphere that is low in oxygen the oxygen atoms to be supplied to the coating may be supplied from the target. A sputtering target comprising a significant proportion of oxygen may be considered "ceramic". As such, preferably the sputtering target is a ceramic sputtering target.

Preferably, the sputtering step is a plasma sputtering step. When the plasma sputtering method is used, films of uniform quality can be obtained and adhesion force of the film is high. In some cases a large scale of target can be used, allowing films to be produced on large glass sizes. The plasma sputtering methods include DC sputtering, RF sputtering, magnetron sputtering, and reactive sputtering. Preferably, the layer comprising cerium oxide is produced by magnetron sputtering. First, argon gas and optionally oxygen gas is introduced into a vacuum chamber at an adequate amount that a voltage can be applied to a cathode where a target material is installed. At this time, electrons released from the cathode collide with gas atoms of Ar gas, thereby ionizing Ar gas atoms to Ar⁺ ions. At that time, electrons are released with argon being excited and thus energy is emitted. Therefore, glow discharge is created. Due to the glow discharge, plasma is formed where ions and electrons coexist. Ar⁺ ions in the plasma accelerate towards the cathode target due to the large potential difference and collide with the surface of the target. As a result, target atoms are displaced and are expelled towards the substrate, forming the coating layer. Preferably, the process further comprising the step of cleaning the surface before the step of sputtering the sputtering target. Such a step may improve the durability and/or appearance of the coating layer. Preferably cleaning the surface comprises one or more of: abrasion with ceria; washing with alkaline aqueous solution; deionised water rinse; and plasma treatment. In addition or alternatively other cleaning methods may be employed such as those known to the skilled person.

Preferably, the sputtering target is a cylindrical sputtering target. Cylindrical sputtering targets may be employed to improve the homogeneity of the produced coating layer and/or to provide high quality coatings in a repeatable manner.

The substrate may be thermally toughened, chemically toughened, and/or bent before application of the layer comprising cerium oxide. However, it is most preferred that the substrate is toughened and/or bent by a heat treatment step after application of the layer comprising cerium oxide. As such, preferably the process further comprises a step of heat treating the soda lime silica glass substrate after the step of sputtering the sputtering target, preferably wherein the step of heat treating the soda lime silica glass substate comprises heating the soda lime silica glass substrate to at least 450 °C for at least 5 minutes.

The inventors have discovered that the layer comprising cerium oxide produced by the present method is suitable for such a heat-treatment, as it does not undergo significant damage as indicated by minimal changes in transparency, haze and durability following heat treatment. As such, the layer comprising cerium oxide is considered "heat-treatable". This is highly beneficial, as the coating may be applied at scale by the glass producer, and then may be cut and toughened as required for vehicular glazings. Therefore, a high quality hydrophobic glass may be provided to vehicular glazing manufacturers that requires minimal processing changes, and preferably does not require changes to manufacturer processing steps.

As described above, in some embodiments the corrosion-resistant coated glass substrate may comprise an underlayer between the layer comprising cerium oxide and the first surface, and preferably the underlayer comprises silicon oxide. Where the coated glass substrate comprises an underlayer this may be formed by a coating method that is the same as, or different from, the coating method of the layer comprising cerium oxide. In one embodiment the underlayer, preferably a silicon oxide underlayer, is produced by a sputtering method, and the layer comprising cerium oxide is produced by a sputtering method. This allows a high quality product to be obtained. The skilled person is aware of methods of providing layers such as underlayers via sputtering.

In an alternative embodiment the underlayer, preferably a silicon oxide underlayer, is produced by a chemical vapour deposition method, preferably an "online" chemical vapour deposition method during the float process, and the layer comprising cerium oxide is produced by a sputtering method. This may allow for increased production speed of product. Deposition of silicon oxide layers using chemical vapour deposition, also known as pyrolytic deposition, may be carried out as disclosed in US 2018118613 Al, incorporated herein by reference. Usually, pyrolytically depositing the underlayer comprises contacting the surface of the substrate with a precursor mixture comprising a source of silicon, a source of oxygen and optionally a radical scavenger. The source of silicon may comprise an oxygenated silicon compound for example a silicon alkoxide (e.g. tetraethylorthosilicate, TEOS), and/or a silicon halide (e.g. silicon chloride). Preferably, however, the source of silicon comprises a silane, more preferably monosilane, Sih The pyrolytic deposition of silicon oxide may be advantageously carried out in conjunction with the manufacture of the glass substrate in the well-known float glass manufacturing process. It was found that a silicon oxide underlayer produced by chemical vapour deposition improved the durability of the coating compared to a sputtered silicon oxide underlayer. In addition, the measured water contact angle of the coating comprising cerium oxide was improved with an underlayer comprising silicon oxide produced by chemical vapour deposition as compared to a coating comprising cerium oxide with an underlayer comprising silicon oxide produced by sputtering.

In some embodiments the underlayer may be applied to the first surface by application of a liquid coating precursor, preferably a liquid coating precursor comprising a silazane, preferably a polysilazane, or an orthosilicate, preferably tetraethylorthosilicate (TEOS). Methods of producing an underlayer from a liquid coating precursor comprising polysilazane are disclosed for example in WO 2017187173 Al, incorporated herein by reference. The method by which the liquid coating precursor is applied to the surface is not normally critical and a variety of techniques may be used. Contacting the surface with the coating composition may, for example, comprise a method selected from dip coating, spin coating, roller coating, spray coating, air atomisation spraying, ultrasonic spraying, and/or slot-die coating. Preferably, the liquid coating precursor is cured following application to provide a coating.

Aspects of the first embodiment may be applied to the second embodiment in any combination, and vice versa.

According to a third aspect of the present invention there is provided the use of a layer comprising cerium oxide as a durable and long-lived hydrophobic surface on a vehicular glazing, wherein: the glass substrate comprises a first surface and a second surface; the layer comprising cerium oxide is directly or indirectly on the first surface; the layer comprising cerium oxide is the outermost layer on the first surface; and the layer comprising cerium oxide comprises from 0.5 to 20 atomic % cerium based on all components.

Aspects of the first and second embodiments may be applied to the third embodiment in any combination, and vice versa.

According to a fourth aspect of the present invention there is provided a vehicle comprising a vehicular glazing according to the first aspect, or manufactured according to the second aspect.

Aspects of the first, second and third embodiments may be applied to the fourth embodiment in any combination, and vice versa.

The skilled person will appreciate that optional or preferable features of aspects of the present invention may be applied to other aspects according to their needs and requirements.

The present invention will now be described by way of example only, and with reference to, the accompanying drawings, in which:

Figure 1 illustrates schematically a vehicular glazing according to an embodiment of the present invention;

Figure 2 illustrates schematically a vehicular glazing according to an embodiment of the present invention, comprising an underlayer. Figure 3 illustrates schematically a cross section of an alternative embodiment of the vehicular glazing of figure 1.

Figure 4 illustrates schematically a cross section of an alternative embodiment of the vehicular glazing of figure 1.

Figure 1 illustrates schematically a vehicular glazing 100 comprising: a substrate of soda lime silica glass with a first surface 101. The first surface comprises a layer comprising cerium oxide - not shown, wherein the layer comprising cerium oxide is the outermost layer on the first surface 101.

Figure 2 illustrates schematically a cross section of an embodiment of the vehicular glazing 100 of figure 1, comprising: a substrate of soda lime silica glass 111 with a first surface 101, and a layer comprising cerium oxide 121 directly on the first surface 101, wherein the layer comprising cerium oxide 121 is the outermost layer on the first surface 101. While in this embodiment the layer comprising cerium oxide 121 is directly on the first surface 101, in alternative embodiments of the invention the vehicular glazing further comprises an underlayer between the layer comprising cerium oxide 121 and the first surface 101. In this embodiment a low-emissivity and/or infrared radiation reflection coating 122 is adjacent to the second surface 102 of the glass substrate 110. In alternative embodiments the low-emissivity and/or infrared radiation reflection coating 122 may be omitted. A further layer comprising cerium oxide may be on the outer surface of coating 122.

Figure 3 illustrates schematically a cross section of an alternative embodiment of the vehicular glazing 100 of figure 1, comprising: a substrate of soda lime silica glass 111 with a first surface 101, and a layer comprising cerium oxide 121 directly on the first surface 101, wherein the layer comprising cerium oxide 121 is the outermost layer on the first surface 101. While in this embodiment the layer comprising cerium oxide 121 is directly on the first surface 101, in alternative embodiments of the invention the vehicular glazing further comprises an underlayer between the layer comprising cerium oxide 121 and the first surface 101. In this embodiment a low-emissivity and/or infrared radiation reflection coating 122 is adjacent to the second surface 102 of the glass substrate 111. In alternative embodiments the low-emissivity and/or infrared radiation reflection coating 122 may be omitted. This embodiment further comprises a further glass substrate 112, adhered to the substrate of soda lime silica glass 111 by an interlayer 131. A further layer comprising cerium oxide may be on the outer surface the further glass substrate 112.

Figure 4 illustrates schematically a cross section of an alternative embodiment of the vehicular glazing 100 of figure 1, comprising: a substrate of soda lime silica glass 111 with a first surface 101, and a layer comprising cerium oxide 121 directly on the first surface 101, wherein the layer comprising cerium oxide 121 is the outermost layer on the first surface 101. While in this embodiment the layer comprising cerium oxide 121 is directly on the first surface 101, in alternative embodiments of the invention the vehicular glazing further comprises an underlayer between the layer comprising cerium oxide 121 and the first surface 101. This embodiment further comprises a further glass substrate 112, adhered to the substrate of soda lime silica glass 111 by an interlayer 131. In this embodiment a low-emissivity and/or infrared radiation reflection coating 122 is between the further glass substrate 112 and the interlayer 131. A further layer comprising cerium oxide may be on the outer surface the further glass substrate 112.

The invention is further illustrated, but not limited, by the following examples.

Examples according to the invention were prepared by sputtering a rotatable ceramic target comprising 65 weight % TiCh and 35 weight % CeCh (corresponding to 80.0 atomic % titanium and 20.0 atomic % cerium based on cerium and titanium, and corresponding to 26.7 atomic % titanium, 6.7 atomic % cerium and 66.7 atomic % oxygen based on all components) with length 23 inches and diameter 5.914 inches. A layer comprising cerium, titanium and oxygen CeTiOx was formed.

Examples 1 to 3 were prepared by sputtering the layer comprising CeTiOx directly onto a sodalime silica glass substrate, while examples 4 to 6 were prepared by sputtering the layer comprising CeTiOx onto an underlayer comprising silicon oxide. The underlayer comprising silicon oxide was produced in these examples using chemical vapour deposition with a thickness of 20 to 30 nm. Comparative Example 1 (CE1) is uncoated float-glass, and comparative example 2 (CE2) is a commercially available PFAS.

The examples were characterised as follows: Water Contact Angle - the average water contact angle (n=5) of 10 x 10 cm samples was measured with deionised water (50 pl deionized water droplet) using a FTA200 with FTA32 software, both available from First Ten Angstroms, Newark, CA, USA. Samples of coated glass substrates were tested after deposition, then again after durability assessment steps, to assess the long-lived nature of the hydrophobic properties.

Table 1 depicts the average water contact angle of examples measured after deposition (AD).

Tablel

From Table 1 it can be seen that substrates with surprisingly high water contact angles of greater than 60° may be obtained with a CeTiOx, compared to untreated glass which has a water contact angle of 25°. A high water contact angle is associated with reduced water-surface energy, resulting in easier water removal from the surface.

Indeed, high water contact angles may be obtained with a coating of only 10 nm thickness. Meanwhile, a coating with a surprisingly high water contact angle may be obtained with a CeTiOx coating of 50 nm, and the aging performance of such a coating is markedly improved by the presence of a silicon oxide underlayer.

As such, in embodiments where a silicon oxide underlayer is desired, it is desirable that the thickness of a CeTiOx layer is greater than 10 nm, preferably 25 nm or greater, more preferably 50 nm or greater, such as from greater than 10 nm to 500 nm, preferably 25 nm to 250 nm, more preferably from 50 nm to 100 nm. It was noticed that water contact angle increases with aging to a stable value. Oil Rub - an oil soaked felt pad is passed over the coated side of the sample, under an added load of 0.9 kg, using a Sheen Instruments Ltd Wet abrasion scrub tester 903. The samples are placed on the equipment with coating uppermost and fixed using clamps. A felt square (1.2cm square) cut from Erichsen felt strips (DIN 68 861) is soaked in Immersion Oil for Microscopy from Merck Chemicals Ltd. This is placed on the glass and rubbed back and forth across the sample surface for 50, or 500, strokes. The samples are examined for scratches and are compared to images from reference samples to be graded on the Oil Rub Test Delamination Scale from 0 to 9, a lower score is better. If all of the coating is removed the sample score is 10. Table 3 depicts the oil rub results and average water contact angle after testing. The water contact angle was measured before and after testing. Preferably a vehicle glazing according to the present invention achieves a score of 5 or less, preferably 3 or less, more preferably 0 when submitted to an oilrub 50 and/or oil rub 500 test as detailed herein. Preferably a vehicle glazing according to the present invention achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following an oil rub 50 and/or oil rub 500 test as detailed herein.

Mini-brush - a wetted Mink brush is passed over the coated side of the sample, under a given load, using a Sheen Instruments Ltd Wet abrasion scrub tester 903. The samples are placed on the equipment with coating uppermost and fixed using clamps. An approximately 2.5 cm diameter sized drop of water is placed onto the sample, directly below the brush head. The brush is placed on the glass and rubbed back and forth across the sample surface for 500 strokes. The samples are examined for scratches and are compared to images from reference samples to be graded with a score from 0 to 4, a lower score is better. A score of 0 can be given for no discernible wear. A score of 1 or 2 is a pass and a score of 3 or 4 is a fail. The water contact angle was measured before and after testing. Preferably a vehicle glazing according to the present invention achieves a score of 5 or less, preferably 3 or less, more preferably 0 when submitted to a minibrush test as detailed herein. Preferably a vehicle glazing according to the present invention achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following an oil rub 50 and/or oil rub 500 test as detailed herein.

Alkali Corrosion testing - Examples and comparative examples were submitted to alkali corrosion testing, wherein heat treated samples were immersed in IM NaOH at 23 °C for 2 hours. The change in haze was assessed (BYK Gardner Haze-gard plus) according to ASTM D1003 as depicted in Table 2, and the change in transmittance was assessed as depicted in Table 3.

Table 2

Table 3

Table 2 shows that all measured samples exhibited extremely low haze both initially and after alkali corrosion testing, indicating excellent corrosion resistance by CeTiOx coatings. Similarly, Table 3 shows that transmittance is reduced by increasing thickness of CeTiOx coating, but is increased, or only slightly reduced, by the presence of a silicon oxide underlayer. The change in transmittance caused by alkali corrosion testing is negligible. Preferably a vehicle glazing according to the present invention achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following an alkali immersion corrosion test as detailed herein.

Acid corrosion testing - Examples and comparative examples were submitted to acid corrosion testing, wherein heat treated samples were immersed in IM HCI at 23 °C for 2 hours. The change in haze was assessed (BYK Gardner Haze-gard plus) according to ASTM D1003 as depicted in Table 4, and the change in transmittance was assessed as depicted in Table 5. Table 4

Table 4 shows that all measured samples exhibited extremely low haze both initially and after acid corrosion testing, indicating excellent corrosion resistance by CeTiOx coatings.

Table 5

Table 5 shows that the change in transmittance caused by acid corrosion testing is negligible.

As such, CeTiOx coatings may be used to produce heat treated coated glass substates with excellent excellent corrosion resistance and preferably the vehicular glazing exhibits a haze increase of 1% or below after 2 hours immersed in IM NaOH or IM HCI at 23 °C. Preferably a vehicle glazing according to the present invention achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following an acid immersion corrosion test as detailed herein.

Preferably, a vehicle glazing according to the present invention passes EN1096 A applied to the surface carrying the cerium oxide coating and achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following one or more of the tests according to EN1096 A. Preferably, a vehicle glazing according to the present invention passes EN1096 B applied to the surface carrying the cerium oxide coating and achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following one or more of the tests according to EN1096 B.

Preferably, a vehicle glazing according to the present invention passes dry abrasion mar resistance test ASTM D6037 applied to the surface carrying the cerium oxide coating and achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following one or more of the tests according to ASTM D6037.

Preferably, a vehicle glazing according to the present invention passes a scratch test according to ASTM E 2546 or ISO 14577 applied to the surface carrying the cerium oxide coating and achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following one or more of the tests according to ASTM D6037 or ISO 14577.

Preferably, a vehicle glazing according to the present invention passes an accelerated UV light aging test according to ASTM D 523 and/or ASTM D 2244 applied to the surface carrying the cerium oxide coating and achieves a water contact angle of at least 30°, preferably at least 40°, more preferably at least 50°, yet more preferably at least 55° following one or more of the tests according to ASTM D 523 or ASTM D 2244.

Furthermore, the coated glass substrate responds very well to heat treatment, as such there is provided a heat treatable coated glass substrate which may be heat treated to produce a heat treated coated glass substrate with durable and long-lived hydrophobic surface and excellent corrosion resistance.

The present specification is concerned with vehicular glazings, for example sidelights, rooflights, windscreens, side windows, quarterlights and the like. In addition, such vehicular glazings include other external glass areas of the vehicle, such as spandrels and finishers, and other internal glass areas of the vehicle, such as displays, consoles, fascia pieces and the like.

Claims

1. A vehicular glazing with a durable and long-lived hydrophobic surface comprising: a glass substrate with a first surface and a second surface; and a layer comprising cerium oxide directly or indirectly on the first surface, wherein: the layer comprising cerium oxide is the outermost layer on the first surface; and the layer comprising cerium oxide comprises from 0.5 to 20 atomic % cerium based on all components.

2. A vehicular glazing according to claim 1, wherein the layer comprising cerium oxide comprises Ce_xTi_yOz and the atomic proportion of Ce based on Ce and Ti in the base layer, calculated as x/(x+y), is from 0.5 to 0.95, more preferably from 0.50 to 0.90, preferably from 0.55 to 0.85, more preferably from 0.60 to 0.80, yet more preferably from 0.62 to 0.67.

3. A vehicular glazing according to claim 1 or claim 2, wherein the layer comprising cerium oxide has a thickness of from 1 nm to 500 nm, preferably from 5 nm to 250 nm, more preferably from 10 nm to 100 nm.

4. A vehicular glazing according to any preceding claim, wherein the layer comprising cerium oxide is the only layer on the first surface.

5. A vehicular glazing according to any of claims 1 to 3, further comprising an underlayer between the layer comprising cerium oxide and the first surface.

6. A vehicular glazing according to claim 5, wherein the underlayer comprises silicon oxide, preferably the underlayer comprising silicon oxide is directly on the first surface, more preferably the underlayer comprising silicon oxide is directly on the first surface and the layer comprising cerium oxide is directly on the underlayer.

7. A vehicular glazing according to any preceding claim, wherein the layer comprising cerium oxide comprises from 1 to 10 atomic % cerium based on all components, preferably from 2 to 8 atomic % cerium based on all components.

8. A vehicular glazing according to any preceding claim, wherein the layer comprising cerium oxide further comprises titanium, preferably the layer comprising cerium oxide comprises from 50 to 95 atomic % titanium based on titanium and cerium, more preferably the layer comprising cerium oxide comprises from 70 to 90 atomic % titanium based on titanium and cerium, even more preferably the layer comprising cerium oxide comprising from 75 to 85 atomic % titanium based on titanium and cerium.

9. A vehicular glazing according to any preceding claim, wherein the layer comprising cerium oxide comprises less than 10 atomic % silicon based on all components, preferably the layer comprising cerium comprises less than 1 atomic % silicon based on all components, more preferably the layer comprising cerium is essentially free of silicon.

10. A vehicular glazing according to any preceding claim, wherein the layer comprising cerium oxide comprises less than 10 atomic % aluminium based on all components, preferably the layer comprising cerium comprises less than 1 atomic % aluminium based on all components, more preferably the layer comprising cerium is essentially free of aluminium.

11. A vehicular glazing according to any preceding claim, wherein the coated glass substrate exhibits a water contact angle of greater than 30°, preferably greater than 50°, even more preferably greater than 60°.

12. A vehicular glazing according to any preceding claim, wherein the second surface comprises a low-emissivity and/or infrared radiation reflection coating.

13. A vehicular glazing according to claim 12, wherein the low-emissivity and/or infrared radiation reflection coating comprises a transparent conductive layer, preferably a transparent conductive silver layer or a transparent conductive metal oxide layer.

14. A vehicular glazing as claimed in any one of the preceding claims, wherein the vehicular glazing is a bent and/or strengthened vehicular glazing.

15. A vehicular glazing according to any preceding claim, wherein the vehicular glazing is a laminated vehicular glazing.

16. A vehicular glazing according to any preceding claim, wherein the vehicular glazing is a windscreen, sidelight, backlight, or rooflight, preferably an automotive windscreen, sidelight, backlight, or rooflight.

17. A process for producing a vehicular glazing according to any of claims 1 to 16, wherein the process comprises: providing a glass substrate with a first surface; providing a sputtering target comprising cerium oxide; and sputtering the sputtering target comprising cerium to provide a layer comprising cerium oxide directly or indirectly on the first surface.

18. A process according to claim 17, wherein the sputtering target comprises titanium, preferably from 50 to 95 atomic % titanium based on titanium and cerium, more preferably the sputtering target comprises from 70 to 90 atomic % titanium based on titanium and cerium, even more preferably the sputtering target comprises from 75 to 85 atomic % titanium based on titanium and cerium.

19. A process according to any of claims 17 to 18, further comprising the step of heat treating the soda-lime silica glass substrate after the step of sputtering the sputtering target, preferably wherein the step of heat treating the soda lime silica glass substate comprises heating the soda lime silica glass substrate to at least 600 °C for at least 5 minutes.

20. A process according to any of claims 17 to 19, further comprising the step of bending the substrate.

21. A process according to claim 20, wherein the step of bending the substrate is before the step of sputtering the sputtering target.

22. A process according to claim 21, wherein the step of bending the substrate is after the step of sputtering the sputtering target.

23. A process according to any of claims 17 to 22, further comprising the step of applying an underlayer to the first surface, preferably the step of applying the underlayer comprises depositing a layer comprising silica by chemical vapour deposition, physical vapour deposition, or liquid deposition, preferably by chemical vapour deposition.

24. Use of a layer comprising cerium oxide as a durable and long-lived hydrophobic surface on a vehicular glazing, wherein: the glass substrate comprises a first surface; the layer comprising cerium oxide is directly or indirectly on the first surface; the layer comprising cerium oxide is the outermost layer on the first surface; and the layer comprising cerium oxide comprises from 0.5 to 20 atomic % cerium based on all components.

25. A vehicle comprising a glazing according to any of claims 1 to 15, or a glazing produced according to any of claims 15 to 22, preferably an automobile.