Patent Application
20220073424
The invention relates to a glazing onto which has been deposited via a process of physical vapor deposition (PVD) under vacuum, mainly cathode-enhanced magnetron sputtering, plasma-enhanced chemical vapor deposition (PECVD) or evaporation or a liquid deposition process, one or more thin layers having spatial structuring at scales which may vary from several cm to less than 10 μm.
The products targeted are varied: silver layers (solar control, low-emissive, electromagnetic shielding, heating), layers modifying the level of reflection in the visible region (antireflection or mirror layers), transparent or non-transparent electrode layers, electrochromic, electroluminescent, anti-iridescent, antisoiling, scratch-resistant or magnetic layers, colored or absorbent layers for modifying the transmittance in the visible region for esthetic purposes.
The products targeted are in particular stacks deposited by magnetron sputtering.
Glazings having a capacity for reflecting both near-IR and/or far-IR waves, as is common in thermal-control glazings, will be thought of, but not exclusively. The function provided is, in this case, either the drastic reduction of the emissivity of the surface of the glazing (thermal insulation) or a substantial reduction in the amount of solar energy passing through the glazing assembly (solar control).
Similarly, glazings covered with a conductive layer which acts as an electrode—for example for a heating function (eglass for building applications, heated windscreen or side windows for motor vehicle or aeronautical applications) or which can serve as an antenna for picking up electromagnetic waves, will be considered.
A particular case concerns the microwave band in the GHz region (100 μm<I<1 m) which finds applications for radio transmissions (GSM, satellite, radar, etc.). Specifically, the possibility of structuring the layer at a scale less than that of the wavelength gives access to the range of metamaterials in which the electromagnetic transmission can be modulated.
For these various functions (antenna, heating, thermal control), the highly conductive and non-earthed layer brings about significant attenuation of high-frequency electromagnetic waves and it is difficult to ensure the compromise between thermal control (hereinabove the case of reducing heating in a vehicle) and good reception of communication signals. The standard attenuation on a windscreen of a thermal control layer may be, for example, from −30 to −45 dB approximately between 0.4 and 5 GHz.
This compatibility of the thermal functions with the transparency to communication waves (for example 2G/3G/4G) is highly demanded for motor vehicle applications and is increasingly demanded for buildings which do not have relays.
There are currently two solutions for overcoming this difficulty: the thermal control function may be provided not by a conductive thin layer but by a polyvinyl butyral (PVB) or other interlayer containing nanoparticles of a conductive compound such as tin-doped indium oxide (ITO, meaning indium tin oxide), for example. In this case, the thermal control is provided by absorption rather than by reflection of the energetic part of the spectrum. This solution is possible only for solar control, and is sparingly efficient relative to the reflection solution and requires laminated glazing.
The second solution consists in etching the silver layer after deposition so as to selectively remove the silver on strips that are thin enough (100 μm) to be barely perceptible to the eye and spaced from each other by a few mm depending on the wavelengths whose transmission it is desired to promote. Complex patterns may be used for this application fully in the face. Representatives of this technique are in particular WO 99/54961 A1 and WO 2014/033007 A1.
In addition, the heating efficiency of a conductive layer depends on its surface resistance Rsq or R□, the voltage between the electrodes, but also the distance between the electrodes. For building applications, this dependency poses a problem since, for the same power supply, an electrical resistance of the glazing is required for each size of heating zone. One solution may consist in etching once more, for example, a silver base layer so as to modulate its overall surface resistance to enable it to be compatible with the distance between electrodes and the desired surface heating power.
Finally, a silver-based glazing may be functionalized in the form of an antenna on condition that the electromagnetic decoupling of the layer with the car body, for example, is performed. This operation is also achieved by etching.
Alternative selective etching methods are essentially derived from the microelectronics industry. Some of them employ temporary layers, others consist of direct etching.
In the microelectronics or photolithography industry: use of temporary layers to serve as masks for selective acid attack. Photolithography allows very fine etching (45-90 nm nowadays industrially), but remains limited to the size of the masks, which at the present time is limited by the size of the optics.
Laser engraving of the conductive layer is performed by a spot engraving laser which sublimes the thin-layer stack by sweeping with the beam. This operation is of low production efficiency on large-sized glazings and requires heavy investment with regard to the surfaces treated.
Ion-impact or electron-impact etching has the same limitations as laser engraving in terms of production efficiency.
Other etching methods come from conventional printing.
At the present time, inkjet printing techniques still remain limited for sizes greater than 10 m2 to printing times of more than a minute.
Other techniques may be favored over screen printing when a resolution scale of less than 50 μm is sought: the reason for this is that this process affords relatively mediocre edge qualities at these small scales.
The aim of the invention is thus the provision of functional glazings which allow radio frequencies to pass through. The term “functional glazing” means herein a thermal-control heated antenna glazing, or the like, a glazing with electrically conductive or non-conductive layer(s), and also all the other glazings mentioned previously. Radio frequencies are high-frequency electromagnetic waves, in the gigahertz region, and find applications in radio transmissions (GSM, satellite, radar, etc.) and communication (for example 2G/3G/4G).
To this end, one subject of the invention is a process for depositing on a glass substrate an essentially mineral functional layer or stack of layers, characterized in that it comprises the steps consisting in
Laser crosslinking of the resin makes it possible to harden it in an extremely fine line, with a width of the order of a few tens of microns or even less, in general between 5 and 100 μm. In the case of lines with a width of 40 μm at most, a heat treatment is not necessary, the line of organic resin and the magnetron layer or stack which covers it may be removed solely by techniques of wiping, blowing with gas, washing, etc. However, a heat treatment may be performed in this case also, in particular in order to give the glass substrate improved mechanical properties.
The technique according to the invention affords an excellent quality of the substrate and in particular of the edges of zones not coated with the organic coating and covered with the mineral layer(s) (sharpness, resolution).
The process makes it possible to produce on an industrial line, on a substrate of large area, an essentially organic coating pattern. The reduced cycle time makes it possible to validate the industrially applicable nature.
According to preferred characteristics of the process of the invention:
Since the glass can no longer be cut once it has been tempered, it may, in certain applications, for example for buildings, be stored and then cut, edged, etc. before tempering. This glazing may be sold in the form as obtained, mainly in this case with the crosslinked solid resin pattern and the magnetron layer or stack removed subsequently with tempering by a transformer, in accordance with the process of the invention.
Preferably, the heat treatment forms part of a thermal tempering of the glass substrate. During tempering, the resin disappears by combustion and consequently removes the essentially mineral functional layer or stack of layers, which may be conductive at the places of the resin patterns, which brings about the desired selective etching.
In one particular embodiment, the heat treatment forms part of a bending of the glass substrate, in particular press bending. In this case, a preliminary heat treatment brings about combustion of the resin, and any pulverulent resin combustion residues and the fraction of the magnetron layer or stack covering the crosslinked resin pattern are then removed via any suitable means, before the pressing tools come into contact with the glass substrate.
According to one variant of the process, after the deposition of the essentially mineral functional layer or stack of layers, at least one essentially organic photosensitive resin—essentially mineral functional layer or stack of layers sequence is deposited again. This deposition is preferably performed before the heat treatment for the combustion of the essentially organic resin that is closest to the substrate, and a subsequent heat treatment will produce the combustion of several superposed essentially organic resins and also the subsequent removal of several essentially mineral functional layers or stacks of layers covering them. However, the deposition of essentially organic resin—essentially mineral functional layer or stack of layers sequences, starting from the second sequence, after the combustion heat treatment of the first essentially organic resin and wiping or removal by blowing with gas of its organic residues and of the mineral residues covering them, also forms part of the invention.
The glass substrate obtained via the process of the invention is also capable of being integrated into a laminated glazing or other laminated composite product, and/or into a multiple glazing.
Other subjects of the invention consist of
The invention will be understood more clearly in the light of the example that follows.
A uniform thickness of a precursor liquid composition of an organic photosensitive resin, sold by the company MicroChem Corp under the registered brand name MicroChem® SU-8 2015, is applied by spin coating to a 15 cm×15 cm glass substrate 4 mm thick, sold by the company Saint-Gobain Glass under the registered brand name Planiclear®.
This liquid composition contains, as mass percentages:
A uniform liquid thickness of 21 μm is deposited at a spin-coating spin speed of 2000 rpm. A spin coater machine of registered brand name Semiconductor Production Systems Europe® (SPS) sold under the reference SPIN150 is used.
The resin is crosslinked locally using a laser sold under the registered brand name Trumpf®, TruMark Station 5000 model. The laser is used at a power of 100%, a focal length of 4.3 mm, a speed of 1000 mm/s and a frequency of 70000 Hz.
The substrate, the crosslinked solid resin pattern and the non-crosslinked liquid resin are placed for one minute in a bath of good solvent for the non-crosslinked resin. It is, in mass percentages:
The substrate, the crosslinked solid resin pattern and the non-crosslinked liquid resin are then removed from the bath and good solvent is then delicately sprayed on using a pipette so as to complete the washing (removal) of the non-crosslinked liquid resin. The good solvent is washed from the surface of the substrate and of the crosslinked solid resin pattern with isopropanol using a pipette. Finally, the substrate and the crosslinked solid resin pattern are dried with a stream of nitrogen.
The lines of the crosslinked solid resin pattern have a width of 30±2 μm and a height of 20±5 μm. The crosslinked resin pattern is a square lattice network with a side length of 3 mm (distance between the centers of two consecutive parallel lines).
A stack of thin layers is deposited in a compliant manner by cathode-enhanced magnetron sputtering onto the glass+crosslinked solid resin pattern system. This stack of thin layers has the following constitution, in which the thicknesses are in nm: Si3N4 20/SnZnO 6/ZnO 7/NiCr 0.5/Ag 9/NiCr 0.5/ZnO 5/Si3N4 40/SnZnO 30/ZnO 5/NiCr 0.5/Ag 14/NiCr 0.5/ZnO 5/Si3N4 28. The ZnO layers are nonporous. This stack with a thermal control function is temperable.
The glass substrate, the crosslinked solid resin pattern and the stack of mineral layers are tempered in a thermal annealing furnace sold under the registered brand name Nabertherm® (N41/H model), at 650° C. for 10 minutes, so as to give the substrate and its stack of mineral layers their final mechanical properties. Tempering also makes it possible to partially remove the crosslinked solid resin pattern, thus detaching the mineral layers which cover it. A mechanical action should be applied so as to fully remove the resin residues; to this end, this mechanical action is sufficient in the absence of the heat treatment since the lines of the crosslinked solid resin pattern have a width of less than 40 μm.
The final product has the stack of thin layers described above structured in a pattern corresponding to the negative of that made with the resin.
The transmission of electromagnetic waves through this glazing and through a comparative glazing, which differs from the glazing of the invention only in the presence of the stack of magnetron mineral layers over its entire surface, is measured.
For frequencies of 0.9, or 2.4, or 5 GHz, respectively, the transmission attenuation of the glazing of the invention, including the magnetron stack except in a grating pattern of 3 mm×3 mm, with a line width of 30 μm, is −9, or −19, or −25 dB, respectively. For the comparative glazing without the grating pattern free of the magnetron stack, it is −25, or −40, or −54 dB, respectively.
Thus, the invention provides a functional glazing with decreased transmission attenuation of waves with frequencies of between 0.4 and 5 GHz.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2018/052836 | 11/14/2018 | WO | 00 |
