IL27704A

IL27704A - Light-transmitting materials with heat-reflecting properties

Info

Publication number: IL27704A
Application number: IL2770467A
Authority: IL
Original assignee: Glaverbel
Priority date: 1966-05-18
Filing date: 1967-03-28
Publication date: 1971-03-24
Also published as: SE333220B; ES350223A1; NL6704581A; DE1596825A1; JPS4827726B1; CH476180A; FR1513724A; BE693528A; LU51136A1

Description

C O H E N Z E D E & S P I S B A C H REGD. PATENT ATTORNEYS 24, LEVONTIN STR.. P. O. B. 1169 T E L - A V I V P A T E N T S & D E S I G N S O R D I N A N C E SPECIFICATION LIGHT-TR SMITTIBG UA SBUM WITH HEA¾?*RBFIiSC IHG PROPERTIES* nT ao on1? HDK ηκ jfr-pjyo tpmn GLAVERBEL, a Belgian Socie e Anonyme, of 166, ©nause^e de la Hulpe , Wa ermaal-Boitsfort, Belgium, (formerly 79, Avenue Louise, Bruxelles 5f Belgium*), REBY DECLARE ihe nature of this invention and in what manner the same is to be performed to be particularly described and ascertained in and by the following statement: This invention relates to light-transmitting materials with heat-reflecting properties.

It is lnown that the transmission of heat radiation through sheets of glass or other light-transmitting material can "be reduced "by applying to such material a thin transparent coating of a metal, e.g., gold, copper or silver, exhibiting a higher degree of transparency to visible light than to infrared radiation. Metal-coated glass has "been widely used for glazing purposes where it is required to shield room interiors from excessive thermal radiation.

Although glass bearing a transparent metal coating can serve as an effective thermal screen, the metal coating affects the light-reflection and/or transmission in ways which are for many purposes undesirable. As an example, if metal-coated glass is used for glazing aerodrome buildings, the light-reflection may be so great as to hazard safety by dazzling pilots of aircraft approaching or leaving the aerodrome. Such glazings may also have an unplesant appearance due to the colour of the reflected light; for example, a gold coating, which has particularly good anti-heat properties, imparts a coppery colour to the glazing. A further disadvantage is that the provision of an effective screen against very strong solar infrared radiation necessitates a metal coating of such thickness that the light transmission is reduced to an undesirably low level.

The present invention makes it possible to retain the valuable anti-heat properties conferred by a metal coating without commitment to the particular light- transmitting and light-reflecting properties which would ordinarily "be conferred on the light-transmitting material by such coating. In other words the invention goes at least some way towards reducing the conflict between required predetermined heat-reflecting properties on the one hand and required predetermined optical properties on the other hand.

It has been found that this result can be achieved by employing a metal layer as one layer of a double- or triple-layer coating forming an interference filter, the other layer, or each of the other layers if there are two of them, being a layer of a dielectric metal compound or compounds.

According to the present invention therefore, a light-transmitting material is provided which comprises a support of glass or other light-transmitting material bearing on at least one face thereof an interference filter formed by a double- or triple-layer coating constituted by a light-transmitting metal layer with a higher degree of transparency to visible light than to infrared radiation, and one or two light-transmitting dielectric layers of a metal compound or compounds, the filter having a substantially different light-reflecting and/or transmitting property than would be possessed by a coating constituted solely by the metal layer.

Advantageously, the invention is employed to confer on glass or other light-transmitting material an apparent colour, viewed by reflected or transmitted light,different from that of a material of like composition save for the In the following further description of the invention sheet glass supports are referred to because the invention is primarily concerned with coated sheet glass but it is to be kept in mind that light-transmitting supports of other transparent or translucent materials, e.g., acrylic, polyvinyl and other plastics materials, can be used.

The metal layer of the interference filters plays a double role in the sense that it confers desirable anti-heat properties as well as co-operating with the dielecitric layer or layers to confer the requisite optical properties, and it is possible to produce coated glass products to meet a wide range of different optical and thermal specifications notwithstanding that in no case does the coating comprise more than three layers.

In emphasising that the invention employs a coating comprising no more than three layers, it is to be understood that supports bearing a double- or triple-layer coating on each face are not excluded.

Suitable optical coating thicknesses for the dielectric layer or layers in order that such layer or layers will function, with a metal layer with the required anti-heat properties, to give the required optical properties, can easily be determined by tests.

It is advantageous for the dielectric layer or layers to have a refractive index or refractive indices higher than 1.7» because the permissible tolerance in coating thickness for realising particular optical properties is then greater.

Dielectric layers often attach to glass more satisfactorily than metal layers and it is an advantage from this point of view for a dielectric layer to underlie the metal layer. In carrying out the invention, preference is given to triple-layer coatings wherein the metal layer is "between two dielectric layers. When two dielectric layers are present the production costs are favourably affected if such layers are of the same composition. In mass production, only two coating installations are then necessary; one for applying the metal layer and the other for applying the dielectric layers.

Preferred dielectric metal compounds for forming dielectric layers are: ZnS, Ti02, CdS, Ce02, CdO, PbO, Sn02, SiO, SbgO^ Zr02, a^.

A dielectric layer may "be formed from one of these oxides or from a mixture of two or more of them.

The following Examples 1 to 5 specify the compositions of various interference filters which may "be employed in materials according to the invention: Example 1 Light-transmitting sheets "bearing on one face a triple-layer coating comprising a layer of gold "between two dielectric layers of i^O^, the layer thicknesses, starting with the dielectric layer underlying the gold layer, being 100-170 A, li+5-180 & and 200-450 S respectively. Glazings so formed appear grey in reflection and do not possess that metallic brilliance which is associated with a gold coating. The glazings nevertheless have good anti-heat properties and are suitable for the curtain walls of buildings, including aerodrome buildings.

Example 2 Transparent sheet supports each having on one face a triple-layer coating comprising a layer of gold having a o thickness of 130-180 A "between two layers of B 2°3 each 195-300 $ in thickness. An anti-heat glazing so produced are slightly coloured in reflection and transmission.

Example 3 Glazings with very good infrared reflecting properties and having a yellow colour in reflection, incorporating a triple-layer interference coating comprising a layer of gold "between two layers of the thicknesses of the layers, starting with the "bottom dielectric layer, being 80-100 A, 160-180 A and 390-410 Ϊ respectively.

Example k Anti-heat glazing with a weak purple colour viewed by reflected light, incorporating a triple-layer interference coating comprising a layer of gold between two layers of the thicknesses of the layers, starting from the bottom layer, being 100-2.+0 $, 190-275 A and o 90-220 A respectively.

Example 5 Anti-heat glazings with a strong purple colour in reflection, incorporating a triple-layer interference coating comprising a layer of gold with a thickness of 130-180 in thickness.

The following are further examples of methods of making particular materials according to the inventions Example 6 A layer of "bismuth oxide 1051 in thickness was deposited on a sheet of glass by evaporation from a crucible in a chamber in which a vacuum of 10~^ mm Hg was maintained. The bismuth oxide in the crucible was vaporized by heating it by electronic bombardment.

During the deposition, the thickness of the layer was measured in terms of the light reflecting power of the coated surface. On the oxide layer there were then o successively deposited a layer of gold 180 A thick and a o layer of bismuth oxide 205 A thick. These layers were deposited in the same manner as the first oxide layer and in the same chamber without interrupting the vacuum between the successive coating operations. The "anti-heat" glazing thus formed had in reflection a slightly bluish-grey tint, while the colour of the glazing viewed by transmitted light was greenish-yellow. The overall energy transmission was 30 and the overall reflection k %> The reflection of light in the visible zone of the spectrum was 17%· It will be understood that similar results can be obtained by following the foregoing example but U3ing any other method for forming the layers on the glass.

Example 7.

An "anti-heat" glazing having a grey reflection was produced by the same process as that described in Example 1, but so that the gold layer was 1Z+7 & in thickness, the underlying bismuth oxide layer was 105 in thickness and the top bismuth oxide layer was Aj.10 A* in thickness. This glazing had a lower light absorbing power than an "anti-heat" glazing with a single gold layer. Its light transmission is 51 .

Example 8 Glass was provided with a triple-layer anti-heat coating, comprising a gold layer 170 % in thickness disposed between two layers of CdS, 125 and 330 % in thickness respectively, the layer 125 A* in thickness being disposed between the glass and the gold layer.

The three layers were deposited in vacuo. This glazing had a very good light transmission and a grey colour in reflection.

Example 9 Glass was provided with a triple-layer anti-heat o coating comprising a bottom cerium oxide layer 150 A in o thickness, a middle gold layer 175 A in thickness and a top layer of cerium oxide 00 in thickness. The cerium oxide layers were deposited in vacuo from a tungsten filament coated with cerium oxide and heated electrically. The gold layer was deposited in a similar manner. The coated glass had a grey colour in reflection. Examp e Q Glass was provided with a triple-layer anti-heat Example 11 A gold layer 177 A5 in thickness was formed on a sheet of glass between two layers of Pe20^, having a. thickness of 115 and 305 * respectively. The layers were deposited "by evaporation in vacuo. the deposited in a slightly oxidising atmosphere. The glazing thus obtained had a grey colour in reflection and possessed an absorption "band in the ultra-violet.

Example 12 A layer of lead was deposited "by evaporation in vacuo onto a sheet of glass and then oxidised in vacuo to PbO by the admission of oxygen into the evacuated enclosure, o thereby producing a lead oxide layer 120 A in thickness. A gold layer 170 * in thickness and a second lead oxide layer 315 in thickness were then deposited on to the first PbO layer.

Example 15 Glass was provided with a triple-layer anti-heat coating comprising a gold layer 175 A* n thickness between o bottom and top titanium oxide layers 117 and 310 A in thickness respectively. The bottom titanium oxide layer was deposited from a solution of titanium ethylate containing 30 gr of titanium oxide per litre of ethyl alcohol. After coating the glass surface with this solution it v/as dried for 10 minutes at a temperature of 100°C and finally fired at a temperature of 500°0.

The gold layer was then deposited from a metallisation solution containing 50 mg of AuCl 50 mg of KOH and 200 g of ^2Q2 per litre of water» The top titanium oxide layer was then formed in the same manner as the bottom layer. The coated glass appeared grey by reflected light.

Example Hi Glass was provided with a triple-layer anti-heat coating comprising a gold layer (formed as in Example 13) having a thickness of 177 A* "between bottom and top layers of Sn02 having thicknesses of 160 and respectively. The Sn02 layers were deposited from a solution containing 90 of SnCl^, H20 and 10 by weight of aqueous formaldehyde containing 1+0% by weight of formaldehyde on the underlayer heated to a temperature higher than 200°C. The coated glass appeared grey by reflected light.

The following are further examples of triple-layer anti-heat coatings which impart a grey colour to the coated glass when viewed by reflected light.

Example 15 o A triple-layer coating comprising a gold layer 175 A in thickness between bottom and top layers of SiO, having o thicknesses of 165 and 1+ A respectively.

Example 16 A triple-layer coating comprising a gold layer 170 in thickness between bottom and t having thicknesses of 110 and 290 Example 17 A triple-layer coating comprising a gold layer 180 in thickness between two layers of Zr02 having thicknesses o of 11+7 and 390 A respectively.

Example 18 o A triple-layer coating comprising a gold layer 170 A in thickness between two layers of ZnS having thicknesses of 11+0 and 355 & respectively.

Example 19 A triple-layer coating comprising a gold layer 173 in thickness between two layers of Ta2° navinS thicknesses o of 11+5 and 395 A respectively.

Example 20 Sheet glass was provided with a triple-layer coating comprising a "bottom bismuth oxide layer 195 * in thickness, a gold layer li+5 A" in thickness and a top bismuth oxide o layer 200 A in thickness. The layers were deposited "by evaporation in vacuo. The resulting "anti-heat" glazing appeared bluish in colour when viewed by reflected light. Viewed by transmitted light, the glazing was light-green in colour. The light reflection of the glazing is 9%.

Example 21 A glazing having a light reflection of the order of was produced by providing a sheet of glass with a triple- o layer coating comprising a "bottom bismuth oxide layer 280 A in thickness, a gold layer 175 A* in thickness and a top o bismuth oxide layer 280 A in thickness. The resulting anti-heat glazing had an energy transmission of 22$. The colour of the glazing, viewed "by transmitted light, was straw-yellow,while the colour viewed "by reflected light was mauve.

Example 22 Sheet glass was coated with a bismuth oxide layer 90 * o in thickness,then with a gold layer 165 A in thickness and finally with a bismuth oxide layer l\Q0 A* in thickness. The coated glass had a strong golden-yellow colour viewed "by reflected light and had an energy transmission of 19%, The coated glass had particularly good heat-reflecting properties. Example 23 Sheet glass was coated first with a bismuth oxide layer 100 A in thickness, then with a gold layer 190 A* o in thickness and finally with a bismuth oxide layer 95 A in thickness. The light reflection of the anti-heat glazing thus o¾tained was 6,3%, The colour of the glazing was weak purple in reflection and straw-yellow in transmission. Example 2k Sheet glass was coated first with a bismuth oxide o o layer 235 A in thickness then with a gold layer 225 A in o thickness, and finally with a "bismuth oxide layer 125 A in thickness. The colour of the r esulting anti-heat glazing was weak purple in reflection and straw-yellow in trans-mission. The light reflection was 5·1 .

Example 25 Sheet glass was coated first with a bismuth oxide layer o o 110 A in thickness, then with a gold layer 270 A in thickness, and finally with a bismuth oxide layer having thick- o nesses of 215 A. The anti-heat glazing was weak purple when viewed in reflection. The light reflection was 11 .

The ratio of the light transmission to the total radiation transmission was higher than in the two preceding Examples. Example 26 A glazing having a strong purple colour in reflection was produced by coating sheet glass firstly with a bismuth oxide layer 60 A* in thickness ,then with a gold layer 150 A o in thickness and finally with a bismuth oxide layer 60 A in thickness. The layers were deposited by evaporation in vacuo. In transmission the glazing was pale green in colour. The light reflection of the glazing was 20 .

Coated glass or other light transmitting material according to the invention may be used in single glazing, or to form one or more than one of the light-transmitting panes of a multiple glazing unit, or as a constituent in safety glazing.

Claims

HAVI G MOW particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that wha we claim is :

1. A light-transmitting material comprising a support of glass or other light-transmitting material hearing on at least one face thereof an interference filter formed hy a double-or triple-layer coating constituted hy a light-transmitting metal layer with a higher degree of transparency to visible light than to infrared radiation, dielectric and one or two. light-transmitting/layers of a metal oxide or oxide the filter having a substantially different light-reflecting and or transmitting property than would "be possessed hy a coating constituted solely by the metal layer.

2. A light-transmitting material according to claim 1, wherein the refractive index of the or each dielectric layer is higher than 1.7·

3. A light-transmitting material according to claim 1 or 2 wherein the or each dielectric layer is formed of at ¾,eas.t one of the following compounds: ZnS,

Ti02, CdS, Ce02, CdO, PbO, SnO≥, SiO, S ^, ZrO≥, Ta^. i+. A light-transmitting material according to any preceding claim wherein there are two said dielectric layers and the metal layer is between them*

5· A light!ftransmitting material according to claim k wherein said dielectric layers have the same composition.

6. A light-transmitting material bearing a triple-layer interference coating oomposed according to any of Examples 1 to 5 herein,

7. A light-transmitting material comprising sheet glass with an interference coating comprising layers of thicknesses and compositions substantially as specified in any of Examples 6 to 26.

8. Sheet glass bearing an interference coating and produced substantially as described in Examples 6 to 26. DATED THIS 27th day of COHEN SPISi CH P.O.BOX 1169, Tii L-A VIV A tt orneys f or Applica nts