Article intended to be tempered that is protected by a temporary layer

Abstract

An article includes a glass substrate comprising two main faces defining two main surfaces separated by edges, the substrate bearing a functional coating deposited on at least one portion of a main surface and a temporary protective layer deposited on at least one portion of the functional coating having a thickness of at least 1 micrometer, wherein the temporary protective layer includes an organic polymer matrix and infrared-absorbing materials.

Claims

1. An article comprising a glass substrate comprising two main faces defining two main surfaces separated by edges, said glass substrate bearing: a functional coating deposited on at least one portion of a main surface, and a temporary protective layer insoluble in water deposited on at least one portion of the functional coating having a thickness between 10 and 50 micrometers, wherein the temporary protective layer comprises an organic polymer matrix obtained from a polymerizable composition comprising (meth)acrylate compounds, and infrared-absorbing materials, the (meth)acrylate compounds that have reacted together representing at least 90%, by weight of the polymer matrix.

2. The article as claimed in claim 1, wherein the infrared-absorbing materials represent 0.5 to 10 parts by weight per 100 parts by weight of the organic polymer matrix.

3. The article as claimed in claim 1, wherein the temporary protective layer leads to: a variation in the transmittance, measured at a wavelength of between 800 and 2000 nm, of greater than 20%, or a variation in the reflection, measured at a wavelength of between 800 and 2000 nm, of greater than 20%.

4. The article as claimed in claim 1, wherein the infrared-absorbing materials have a weight loss onset temperature above 300° C.

5. The article as claimed in claim 1, wherein a ratio of the thickness of the temporary protective layer to a mean size of particles forming the infrared-absorbing materials is greater than 3.

6. The article as claimed in claim 1, wherein the infrared-absorbing materials are chosen from pigments chosen from carbon black, aniline black pigments, iron oxide black pigments, titanium oxide black pigments.

7. The article as claimed in claim 1, wherein the polymer matrix represents at least 80% by weight of the temporary protective layer.

8. The article as claimed in claim 1, wherein the glass substrate bearing the functional coating has not undergone heat treatment at a temperature above 400° C.

9. The article comprising a substrate as claimed in claim 1, wherein the functional coating comprises a stack of layers successively comprising, starting from the substrate, an alternation of n functional metallic layers based on silver or on a metal alloy containing silver, and of (n+1) antireflection coatings, each antireflection coating comprising at least one dielectric layer, so that each functional metallic layer is positioned between two antireflection coatings.

10. A process for obtaining an article treated at high temperature, the article comprising a glass substrate comprising two main faces defining two main surfaces separated by edges, said glass substrate bearing a functional coating deposited on at least one portion of a main surface, said process comprising: a step of protecting the article comprising: preparing a polymerizable composition comprising (meth)acrylate compounds and infrared-absorbing materials, the (meth)acrylate compounds that have reacted together representing at least 90%, by weight of the polymer matrix, applying the composition on at least one portion of the functional coating over a thickness between 10 and 50 micrometers, crosslinking the composition so as to form the temporary protective layer, said temporary protective layer being insoluble in water, a same step of heat treating and deprotecting the article comprising: removing the temporary protective layer by heat treatment at a temperature above 200° C. and sufficient to achieve the tempering of the article.

11. The process for obtaining an article as claimed in claim 10, wherein the functional coating is deposited by magnetron sputtering and wherein the temporary protective layer is directly in contact with the functional coating.

12. The process for protecting an article as claimed in claim 10, wherein: the temporary protective layer is crosslinked by UV crosslinking, the polymerizable composition is applied by roller coating.

Description

EXAMPLES

(1) 1. Substrates Coated with the Functional Coating

(2) The substrates used are flat glass substrates having a thickness of around 6 mm obtained by a float process.

(3) The functional coatings comprise a stack of thin layers deposited by means of a magnetron sputtering device.

(4) The stack of thin layers successively comprises, starting from the substrate, an alternation of three dielectric coatings and of two silver layers (functional metallic layers), each dielectric coating comprising at least one dielectric layer, so that each functional metallic layer is positioned between two dielectric coatings. The layer of the functional coating furthest from the substrate is a 1 to 5 nm layer of titanium zirconium nitride. The total thickness of this functional coating is between 150 and 200 nm.

(5) 2. Preparation of the Polymerizable Compositions

(6) The polymerizable compositions were prepared. These compositions comprise polymerizable organic compounds, polymerization initiators and optionally additives and infrared-absorbing materials.

(7) The polymerizable organic compounds comprise oligomers, monomers and optionally prepolymers. A mixture of oligomers and monomers comprising at least one acrylate function sold by Sartomer was used with, in particular: CN9276: tetrafunctional aliphatic urethane-acrylate oligomer, SR351: trimethylolpropane triacrylate, trifunctional acrylate monomer, SR833S: tricyclodecane dimethanol diacrylate, difunctional acrylate monomer.

(8) The presence of the urethane-acrylate oligomer makes it possible to adjust the hardness and flexibility properties of the temporary protective layer.

(9) The polymerization initiator used in these examples is Irgacure® 184, sold by BASF.

(10) The infrared-absorbing material tested is carbon black sold under the name Monarch 120 by CABOT. The mean size of the particles measured according to standard ISO 22412:2017 by cumulant analysis is between 500 and 750 nm. The carbon black has a weight loss onset temperature, measured by TGA, above 500° C. and below 650° C.

(11) The various constituents and additives are mixed by ultrasonic mixing.

(12) The compositions tested are defined in the table below in parts by weight.

(13) TABLE-US-00001 Compositions E C1 X2 B3 A4 Polymer matrix: acrylate oligomer 60 60 60 60 60 difunctional acrylate 20 20 20 20 20 trifunctional acrylate 20 20 20 20 20 UV initiator +10 +10 +10 +10 +10 Carbon black 0 1 2 3 4
3. Preparation of the Articles Tested

(14) TABLE-US-00002 Articles V C1′ X2′ B3′ A4′ Substrate without functional coating Yes Yes Yes Yes Yes Polymerized composition No C1 X2 B3 A4

(15) TABLE-US-00003 Articles F E C1 X2 B3 A4 Substrate + Functional coating Yes Yes Yes Yes Yes Yes Polymerized composition No E C1 X2 B3 A4

(16) The polymerizable compositions are applied on substrates made of glass coated with the functional coating by roller coating (Meyer). The applicator roller rotates at a speed of between around 15 and 25 m/min. The thicknesses of polymerizable compositions deposited are between 10 and 20 μm.

(17) The temporary protective layers are obtained by crosslinking by UV radiation provided by a mercury lamp with a power of 120 W. During this step, the article travels at a speed of 15 m/min. The thickness of the temporary protective layer obtained under these conditions is from 10 to 20 μm.

(18) All the compositions tested crosslinked satisfactorily. Insofar as these polymerizable compositions do not comprise solvent, the amounts of infrared-absorbing materials in the polymerizable composition are substantially equal to the amounts of absorbent materials in the temporary protective layer.

(19) The polymer matrix is obtained by crosslinking polymerizable organic compounds. The proportion of the polymerizable compounds in the polymerizable composition is substantially equal to the proportion of polymer matrix in the temporary protective layer.

(20) These examples show that a temporary protective layer comprising up to 4 parts by weight of absorbent materials par 100 parts by weight of polymer matrix has a thickness within the required range. It may be applied and crosslinked at run speeds compatible with the run speeds used in industrial magnetron sputtering deposition processes, for example a continuous in-line functional coating deposition process.

(21) 4. Tempering Tests

(22) Tempering tests using a vertical furnace were carried out. The vertical furnace makes it possible to simulate, in a laboratory, the tempering conditions. The glass is held vertically by means of a system of clamps, on a mobile support. This support is automatically inserted into the furnace that is above the requested temperature. Once the tempering time has elapsed, the support comes back down and the glass is subjected to a jet of cold air on its two faces using a system of nozzles. The furnace has no convection and the temperature is regulated with the aid of 3 thermocouples located at three different locations. The following parameters are set: Furnace temperature: 730° C., Tempering time: Variable, Cooling time: 100 s, Cold air pressure: 0.7 bar.

(23) For each article, the shortest tempering times were determined. It is verified that the tempering is satisfactory via fracture tests.

(24) a. Determination of the Minimum Tempering Times

(25) The minimum tempering times that make it possible to obtain the required properties were determined. These times correspond to the minimum times to: obtain a good-quality glazing with in particular absence of breakage, absence of iridescence, absence of corrosion of the functional coating, good flatness, obtain a glazing having a satisfactory fragmentation, and remove the temporary protective layer.

(26) The time savings are calculated in the following manner:

(27) $G=\frac{\begin{array}{c}.Math.\mathrm{Tempering}\mathrm{time}\mathrm{of}\mathrm{the}\mathrm{article}\mathrm{to}\mathrm{be}\mathrm{defined}-\\ \text{Tempering time Article}F.Math.\times 100\end{array}}{\text{Tempering time article}F}$

(28) TABLE-US-00004 Tempering Art. time Saving Removal of the layer Frag. V 109 s — — OK F 190 s — — OK E 150 s — Black residues visible after wiping OK (FIG. 1) C1 120 s >35% Black powder removed by wiping OK X2 100 s >45% Black powder removed by wiping OK B3 100 s >45% Black powder removed by wiping OK A4  90 s >55% Black powder removed by wiping OK

(29) Frag.: Fragmentation

(30) FIG. 1 shows an article comprising a functional coating protected by a temporary protective layer as described in application WO 2015/019022. This article was subjected to a heat treatment for a time of greater than 150 s. Black residues corresponding to a portion of the unburnt temporary protective layer were observed. These residues cannot be removed by wiping.

(31) For the articles according to the invention, the high-temperature heat treatment step is shorter, only a few residues are present but can be removed by wiping.

(32) b. Determination of the tempering quality

(33) The quality of the tempering was tested by fragmentation. The articles are broken. FIG. 2 represents photographs of the articles V, C1, X2, B3 and A4 that have undergone the fragmentation test. It is observed that for each article the fragmentation is satisfactory. This is expressed by the observation: of the number of fragments, of the maximum size of the fragments and of the appearance of the edges.
5. Absorption Properties of the Temporary Protective Layers

(34) Measurements of transmittance and reflection were carried out at various wavelengths on various articles.

(35) FIG. 3 represents a graph illustrating the transmittance as a function of the wavelengths for the articles V, F, C1, X2 and A4.

(36) FIG. 4 represents a graph illustrating the reflection as a function of the wavelengths for the articles V, F, C1, X2 and A4.

(37) TABLE-US-00005 Transmittance (T) and Reflection (R) 800 nm 1250 nm 1500 nm 1750 nm 2000 nm Article T R T R T R T R T R V 86% — 84%  — 86% — 88% —  87% — C1′ 36% — 38%  — 42% — 45% —  47% — X2′ 18% — 21%  — 24% — 26% —  28% — A4′  5% — 7% —  8% — 10% —  11% — F 14% 69% 2% 93%  1% 96% 0.6%  97% 0.3% 98% E 14% 72% 2% 90%  1% 93%  1% 93% 0.8% 95% C1  4% 14% 1% 19% 0.5%  21% 0.3%  25% 0.3% 26% X2  2%  8% 0.5%.sup.  10% 0.3%  12% 0.2%  12% 0.2% 15% A4  1%  6% 0.1%.sup.   5% 0.1%   5% 0.1%   6% 0.1%  6%

(38) The variations in transmittance or reflection induced by the temporary protective layer, ΔT=|T.ref−T.pro| and ΔR=|R.ref−R.pro|, are calculated with: T.ref and R.ref being the transmittance or reflection at a wavelength between 800 and 2000 nm of an article that does not comprise a temporary protective layer and T.pro and R.pro being the transmittance or reflection of the same article comprising the temporary layer.

(39) The variation in the transmittance in the infrared induced by the temporary protective layer was calculated by taking as reference: article V for articles C1′, X2′ and A4′, article F for articles E, C1, X2 and A4.

(40) TABLE-US-00006 Δ T Δ T Δ R Δ R at 800 nm at 2000 nm at 800 nm at 2000 nm C1′ 50%  40% — — X2′ 68%  59% — — A4′ 81%  76% — — E  0% 0.5%  3%  3% C1 10%   0% 55% 72% B3 12% 0.1% 61% 83% A4 13% 0.2% 63% 92%

(41) The presence of the temporary protective layer comprising infrared-absorbing materials leads to a variation in the transmittance of greater than 20% or a variation in the reflection of greater than 20% at a given wavelength between 800 and 2000 nm.