Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
  • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
  • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
  • C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
  • C03C17/3626—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer one layer at least containing a nitride, oxynitride, boronitride or carbonitride
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
  • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
  • C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
  • C03C17/3649—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer made of metals other than silver
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
  • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
  • C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
  • C03C17/3657—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer the multilayer coating having optical properties
  • C03C17/366—Low-emissivity or solar control coatings

Definitions

• the present disclosure relates in general to a reflective glass, and more specifically to a heat treatable reflective glass.
• Reflective glass is becoming more and more popular in residential, commercial, and interior applications, e.g., as a decorative item, for fagade applications etc.
• Conventional reflective glass products used in interior applications often comprise of silver based coatings on annealed glass.
• Such reflective glass products based on the annealed glass are considered to be unsafe for interior applications due to their ability or tendency to break/shatter into large shards or sharp pieces
• Glass substrates covered with enamel-based coating are also known in the art.
• enamel coated glass substrates that can be tempered are also known.
• a glass sheet may be covered with a layer of organic paint and the coated glass sheet (also called lacquered sheet) may then be cured in an oven.
• the coated glass sheet also called lacquered sheet
• the paint burns and may result in the paint being damaged or completely destroyed.
• a glass sheet can be tempered before being enamelled.
• this may require the glass sheet to be cut into desired dimensions before being tempered, as a tempered glass sheet is very difficult to be cut.
• enamels free from organic contents need immediate tempering on the same production line, which constitutes a severe limitation from an industrial viewpoint.
• Various processes have been used to develop temperable glass products, which often involve coating one or more layers of enamel which is then dried and/or cured in an oven before being sent to tempering furnaces.
• Mirrors typically have a layer of protective organic paint coated on the silver layer.
• the protective organic layer burns and is deteriorated which eventually leads to the oxidation/damage of the silver layer, thus causing defects in the mirror.
• conventional mirrors generally do not survive heat treatments at temperatures higher than 200 or 250 °C without suffering from some form of degradation.
• the toughening temperature required for any glass is ideally more than 550 °C.
• a heat treatable glass in one aspect of the present disclosure, includes a glass substrate comprising a reflective stack and an enamel layer.
• the reflectance of the heat treatable glass is greater than at least about 20% and less than at least about 70%.
• a method of manufacturing a heat treatable glass includes providing a reflective stack on the first side of a glass substrate.
• the method also includes coating an enamel on the second side of the glass substrate or, above the reflective stack. The second side is opposite to the first side of the glass substrate.
• the method further includes drying the enamel so that the enamel hardens and sticks to the glass substrate but is yet to fuse or sinter.
• FIG. 1 illustrates a schematic cross-sectional view of a heat treatable glass, in accordance with one embodiment of the present disclosure
• FIG. 2 illustrates a schematic cross- sectional view of the heat treatable glass, in accordance with another embodiment of the present disclosure
• FIG. 3 illustrates a block diagram of a reflective stack on the heat treatable glass, according to one embodiment of the present disclosure
• FIG. 4 illustrates a block diagram of the reflective stack on the heat treatable glass, according to another embodiment of the present disclosure.
• FIG. 5 illustrates a flowchart for a method of manufacturing the heat treatable glass, according to an embodiment of the present disclosure.
• Embodiments disclosed herein are related to a heat treatable glass 100.
• FIGS. 1 and 2 illustrate a schematic cross-sectional view of a heat treatable glass 100, according to two different embodiments of the present disclosure.
• the glass product can be heat treated e.g., heat strengthened and/or thermally tempered. Further the glass product can be handled, cut into various sizes, shapes, and transported, both before and after being tempered, as needed without incurring damage because of the above said processes.
• the heat treatable glass of the present disclosure is also a reflective glass having a reflectance ranging between 20% and 70%.
• the heat treatable glass 100 of certain example embodiments has a reflective stack 108.
• the reflective stack 108 may comprise of at least one of the metal and their alloy belonging to the group consisting of niobium, chromium, nickel, tantalum or zirconium.
• FIGS. 3 and 4 illustrate a block diagram of the reflective stack 108 of the heat treatable glass 100, according to different embodiments of the present disclosure.
• FIG. 5 illustrates a flowchart for a process that may be used to manufacture the heat treatable glass 100, in accordance with one example embodiment.
• the heat treatable glass 100 includes a glass substrate 102 having a first side 104 and a second side 106 opposite to the first side 104.
• the heat treatable glass 100 includes a reflective stack 108 on the first side 104 of the glass substrate 102.
• the heat treatable glass 100 further includes an enamel layer 110.
• the enamel layer 110 is above the reflective stack 108.
• the enamel layer 110 is on the second side 106 of the glass substrate 102. In such a case, the enamel layer 110 may be in direct contact with the glass substrate 102.
• the term "reflective stack 108" used herein refers to a stack of thin functional layers and optionally one or more over-layers.
• the term “enamel” used herein refers to an enamel composition before any drying or heat treatment and to an enamel composition which is dried but not yet sinterised and to an enamel composition after heat treatment, which is sinterised.
• the enamel layer 110 may be in direct contact with the coated glass substrate 100.
• the thickness of the coating comprising enamel composition, once dried and before heat treatment, may be at least about 50-120 microns.
• coated glass substrate 100 used herein may refer to the glass substrate 102 having the reflective stack 108 thereon.
• Various embodiments of the reflective stack 108 and the coated glass substrate 100 having the reflective stack 108 will be explained hereinafter.
• SGG Cool-lite Platinum (ST- 108) from Saint-Gobain is a reflective glass product manufactured by depositing a thin stack of Si 3 N 4 /Nb/Si 3 N 4 onto a clear or body-tinted float glass by a magnetically enhanced sputtering process.
• ST- 108 comprises a reflective layer having a stack of thin functional layers comprising of Si 3 N 4 , Nb and Si 3 N 4 .
• the coated glass substrate 100 may be SGG Mirastar from Saint-Gobain, having the reflective stack 108, in accordance with the embodiment of FIG. 4.
• the coated glass substrates 100 of certain example embodiments comprise of yet another reflective layer.
• SGG Mirastar from Saint-Gobain is a reflective glass product comprising the reflective layer having a stack of thin functional layers comprising of Si0 2, Cr and SiN and Ti.
• coated glass substrates 100 of certain example embodiments comprise of yet another reflective layer comprising atleast one of the metal and their alloy belonging to the group consisting of niobium, chromium, nickel, tantalum or zirconium and one or more over layers.
• the coated glass substrates 100 with an enamel in certain example embodiments provide a reflective surface which may be used for interior applications.
• the coating of certain example embodiments comprises of an enamel having about 5 - 40 wt % of organic contents in the form of resin.
• the enamels of certain example embodiments comprise of a powder made of glass frit, organic content, pigments, and a medium.
• the medium ensures that the solid particles are in correct suspension and allows application and temporary adhesion of the enamel to the substrate.
• the medium may comprise one or more alkyds, acrylic, acrylamide, polyols, melamine, acrylic - styrene, vinyl-acrylic, urethane (polyurethane), polyester, urethane alkyds, amino resins, polyamide, epoxy, epoxy ester or phenolic resins.
• Other mediums may be silicon resins, PVC, PVB, or water-based resins.
• the coating of certain example embodiments comprises between 5 and 40% of an organic material which may be prepared by mixing, amongst others, glass frit, pigments with the desired amount of organic solvent.
• a suitable pigment is selected to achieve a desired color on the reflective glass substrate.
• the enamel of the current disclosure is supplied by Ferro and has an inorganic content of 69.8%, an organic content of 12-13% and the rest is in the form of a solvent used for the application.
• the fineness of the grind which represents the size of the particles in the enamel is less than 20 ⁇ measured by the Hegman gauge.
• any enamel having an inorganic content of 30-80% and an organic content of 5-40% may be suitable.
• the solvent evaporates after drying and/or some low molecular weight polymers particularly resin are burned off during heat treatment leaving inorganic contents in the form of pigments and glass frits.
• the enamel layer 110 of the current disclosure may be continuous and extend over substantially the whole surface of the coated glass. Reflection of the glass substrate 102 is subjective to changes during heat treatment, depending on the composition of the coating. However such changes in reflection should remain within acceptable limits such that the aesthetics and resulting functionalities are not compromised.
• reflection may change during heat treatment, depending on the composition of the coating. If this occurs, this should be taken into account on the heat treatable glass 100 that such a reflection change is within the acceptable limit without compromising the aesthetics and functionality.
• the glass substrate 102 used may be of various thicknesses (between 1.5 and 10 mm, for example) whereas the coated glass substrate 100 having the reflective stack 108 and an enamel layer 110 according to the present disclosure may have a thickness depending purely on the coating methodology such as roller, curtain or screen printing.
• the enamel layer 110 may be applied by any method known in the art, for example processes of roller, curtain, spray coating or any other flow process suitable for the coating.
• the enamel layer 110 may be applied by screen printing method, especially if only portions of the glass are to be coated, or by a digital printing method.
• a heat treatable glass 100 according to the present disclosure is heat treated, the organic medium burns in the form of carbonaceous gases and the glass frit melts; the enamel is fused in to the coated glass.
• the viscosity of the enamel may be adjusted based on the selected application technique and/or apparatus.
• the viscosity of the material may be lowered, e.g., by adding diacetone alcohol or the like.
• Adhesion promoters in the form of cross linkers and/or the like also may be added in certain example embodiments.
• the heat treatable glass 100 with the enamel layer 110 can be heat treated (e.g., heat strengthened and/or thermally tempered) at high temperatures, and they can be handled and transported both before and after heat treatment without damaging the enamel layer 110.
• the heat treatable glass 100 with the enamel layer 110 may be cut, ground, have holes drilled therein, etc., without causing the coating to peel off or to become damaged at the borders of the cutting line and drilling holes, before heat treatment.
• the heat treatable glass 100 also offers good water resistance, and the coatings do not peel off or degrade during edge grinding, storage, transportation, etc.
• a method of manufacturing the heat treatable glass 100 may comprise the following steps, in the order recited.
• the method 500 includes providing the reflective stack 108 on the first side 104 of a glass substrate 102.
• the method 500 includes providing the coated glass substrate 100 comprising a reflective layer having a stack of thin functional layers comprising of Si 3 N 4 , Nb, and Si 3 N 4 and one or more over-layers comprising at least one of the metal oxide belonging to the group consisting of Sn, Ti, Ta or Si.
• the method 500 includes coating an enamel layer 110 on one of the second side 106 of the glass substrate 102 or, above the reflective stack 108, wherein the second side 106 is opposite to the first side 104.
• the method 500 includes applying a coating of the enamel through a standard curtain coating methodology during which the glass substrate 102 passes through a continuous falling curtain of the enamel where the enamel gets deposited evenly onto the glass.
• the method 500 includes drying the enamel so that the enamel hardens and sticks to the glass substrate 102 but is not yet fused or sinterised.
• the method 500 includes drying of the enameled coated glass substrate 100 using a two-step methodology wherein the first step comprises of the coated glass substrate 100 being passing through a drying oven where the excess solvent gets evaporated giving some strength to the coating; In the second step the coated substrate goes to the final oven where final drying takes place at temperatures between 160 - 210°C. The temperature depends on the thickness of the enamel layer 110.
• the method 500 may also include washing, cutting, and/or grinding into any shape or size giving freedom to the customer for his requirement/application before being tempered.
• the method may further include heat treating the enameled coated glass substrate 100, wherein both convection and rendition methodology can be used for the tempering.
• the enameled coated glass substrate 100 passes through the furnace at a certain speed and is heated in the temperature zones.
• the standard rule is that the glass is heated for approximately 45 sec per mm of glass substrate 102 and in a temperature ranging between 620-700°C for the tempering effects.
• the enameled coated glass substrate 100 of the current disclosure may advantageously offer good properties in terms of mechanical resistance of the coating. Different tests were used to simulate transportation by truck and evaluate if the coating offered resistance to such transportation without deterioration or with an acceptable level of deterioration without affecting the aesthetics of the glass products.
• the thickness of the coating reduces by approximately 25-30% of the original thickness after the heat treatment.
• the reflection value of the coated glass substrate 100 may change post heat treatment.
• the gloss value was found to be increased post heat treatment. Scratch resistance was also found to be increased post tempering.
• the enameled coated glass substrate 100 of the current disclosure once heat treated may furthermore advantageously offer properties such as better scratch resistance, moisture resistance and abrasion resistance.
• the heat treatable glass 100 thus manufactured may have a reflective value greater than at least about 20% and less than at least about 70%.
• the heat treatable glass 100 according to the current disclosure once heat treated may be used as partitition glass and also for various interior applications and optionally as fagades in buildings, in accordance with standard EN 12150- 1:2000.
• the heat treatable glass 100 according to the current disclosure once thermally toughened breaks according to the fragmentation test of standard prEN14-179-l:2001 or EN1863-1:2000.
• a 300 x 300 mm, SGG Cool-lite Platinum (ST- 108) sample from Saint-Gobain (magnetron coated stack of Si 3 N 4 /Nb/Si 3 N 4 /Glass) of thickness 4mm/6mm was used as a glass substrate 102 along with a solvent based enamel.
• the enamel used was supplied by Ferro having an inorganic content of 69.8%, organic content of 12-13% and the rest was in form of a solvent. Fineness of the grind was less than 20 ⁇ measured by the Hegman gauge. Glass frits were applied to the coating side of the glass using a bar coater to create a uniform coating. The glass substrate was then allowed to cure in an oven at 180 °C for approximately 15 minutes.
• the coating thickness measured was approximately 40 - 125 ⁇ .
• the samples were then cut into 100 mm x 100 mm and the reflectance (%) was measured.
• the samples were then tempered at 640 °C for approximately 8 minutes and allowed to cool. The reflectance was then measured again after heat treatment.
• a 300 x 300 mm SGG Mirastar reflecting glass sample (magnetron coated stack on Planiclear glass//Si0 2 /Cr/SiN/Ti) of thickness 8 mm was used as a glass substrate 102 along with a solvent based enamel.
• the enamels used were supplied by Ferro having an inorganic content of 69.8%, organic content of 12- 13% and the rest was in form of a solvent. Fineness of the grind was less than 20 ⁇ measured by the Hegman gauge. Approximately 27+5 gms of the enamel containing glass frits was applied on the coating side of the glass using a bar coater to create a uniform coating.
• the glass substrate was then allowed to cure in an oven at 180 °C for approximately 15 minutes.
• the coating thickness measured was approximately 50-125 ⁇ .
• the samples were then cut into 100 mm xlOO mm and the reflectance (%) was measured.
• the samples were then tempered at 640 °C for approximately 8 minutes and allowed to cool.
• the reflectance was then measured again after tempering.
• a similar procedure was followed to create a heat treatable reflective glass product using Mirastar where the coating of the enamel was done on the glass side.
• Abrasion (Taber) weight ⁇ 0.07% ⁇ 0.10% 0.021
• the tape test was used to evaluate the adhesion of a coating on a particular substrate. This test was performed as per the standards set out in ASTM Standard D 3359 - 00. A cross hatch pattern was made through the film to the substrate. Detached flakes of coating were removed by brushing with a soft substrate. Pressure Sensitive tape was applied over the cross hatch cut. Tape was smoothed into place by using a pencil eraser over the area of the incisions. Tape was then removed by pulling it off rapidly back over itself as close to an angle of 180°. Adhesion was assessed on a scale between 0 to 5. Brush Test
• the brush test was used to evaluate the resistance of the coating to erosion caused by scrubbing. This test was performed as per the standards set out in ASTM Standard D 2486 - 00. Samples of coated glass were submitted to Test Method A. The sample was scrubbed dry, with a bristle brush until the coating was pierced. Lucite Test
• the Lucite test was used to evaluate the scratch resistance of the coating.
• the sample was sprinkled on the coating side with Lucite ⁇ (R)> 4F or 47G (a quarter of a tea spoon on a sample of 15 x 25 cm), and then covered with a piece of clear glass of 6 mm thick (10 x 10 cm) on which a weight of 1 kg was placed.
• the assembly "upper glass and weight” was subjected to a backward and forward movement during 100 cycles by placing on a lab shaker.
• the hardness test was conducted to check the surface hardness or wear/scratch resistance of a coating on a substrate. This test was performed as per the standards set out in EN 438-2. A hardness test pen having a tungsten carbide tip was drawn over the surface of a substrate having a coating with a defined constant pressure. The pressure on the tip can be changed using the slide or by changing the spring. A visual mark on the surface indicates a fail of the wear/scratch resistance.
• Taber abrasion test was used for performing accelerated wear resistance testing. It involved mounting a flat sample of approximately 100 mm to a turntable platform that rotate on a vertical axis at a fixed speed. The wear action was carried out by two rotating abrading wheels supported on a loading arm which applied 250 gram pressure against the specimen, exclusive of the weight of the wheel in contact with sample. The weight before and after the test was measured to calculate the overall weight loss of the samples.
• the heat treatable glass 100 may have various applications.
• the heat treatable glass 100 may, for example be used for various interior applications of buildings including but not limited to decorative purpose, wardrobes, as doors for furniture, as partitions, in tables, shelves, in bathrooms, in shops displays, as wall covering, as spandrels etc.
• the heat treatable glass 100 may also be used on automotive glazing panels, or at least on portions of these glazing, for example on the peripheral portions of a windscreen or as interior portions of automobiles. More and more of these applications necessitate tempered reflective glass, as the tempered reflective glass has the advantage of being more resistant to breakage. Other heat treatments are also becoming often used: bending, for example.
• the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion.
• a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus.
• “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

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• Chemical & Material Sciences (AREA)
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• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Surface Treatment Of Glass (AREA)
• Laminated Bodies (AREA)
• Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

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Citations (3)

• 2017
  • 2017-05-03 IN IN201641015929A patent/IN201641015929A/en unknown
  • 2017-05-03 WO PCT/IN2017/050158 patent/WO2017191655A1/en not_active Ceased
• 2018
  • 2018-10-10 PH PH12018502176A patent/PH12018502176A1/en unknown

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