GB2396843A

GB2396843A - A method for applying a pattern to a glass panel

Info

Publication number: GB2396843A
Application number: GB0326833A
Authority: GB
Inventors: William Gerard Carey
Original assignee: Carey Brothers Ltd
Current assignee: Carey Brothers Ltd
Priority date: 2002-11-18
Filing date: 2003-11-18
Publication date: 2004-07-07
Anticipated expiration: 2023-11-18
Also published as: GB2396843B; IES20020887A2; IE20030854A1; GB0326833D0

Abstract

A method for applying a pattern (10) to a grass panel for simulating a Georgian style lattice window comprises applying a surface coating composition to form bands (14,15) of the pattern (10) by airless spraying through a nozzle (20). The surface coating composition comprises a mineral based ink of the type suitable for ceramics applications which is provided in powder form of particle sizes in the range of 1 micron to 7.6 microns. The mineral based ink is mixed with a liquid solvent for agglomerating the particles, and colour pigment is added as appropriate. The surface coating composition is applied to an inner surface (11) of the glass panel (3) to a depth of approximately 200 microns to form the bands (14,15), although the surface coating composition may be applied up to a depth of 1,200 microns. The surface coating composition of the bands (14,15) is then dried, and the panel (3) is then toughened at a toughening temperature of the order of 700{C for a time period of approximately one and a half minutes, which also causes the surface coating composition forming the pattern (10) to fuse to the glass.

Description

"A method for applying a pattern to a glass panels The present invention

relates to a method for applying a pattem to a glass panel, and the invention also relates to a glass panel having a pattern applied thereto by the method. The invention further relates to a double glazed unit for a window There are many instances in which it is desirable to apply pattern to a glass panel, and in particular, there are many instances where it is desirable to apply the pattern to the glass panel so that the pattern is clearly defined by well defined edges, rather to than by feathered edges. For example, in the provision of simulated Georgian and Tudor style lattice type windows, It is desirable that the cnss<ross bars of the pattern simulating the lattice appear to be genuine Cries cross bars In the manufacture of double glazed windows where each window pane is formed by a double glazed unit comprising two glass panels, namely, an inner glass panel and an outer glass panel which are spaced apart one from the other, it is known to locate spacer bars which are arranged in a cnss-cross manner between the inner and outer glass panels for simulating a:;eorgian or Tudor style lattice. Typically, such spacer bars are of metal, for example, hollow box section aluminium, and are of thickness corresponding to the spacing between the inner and outer glass panels, which typically, is 12mm. The width of the spacer bars depends on the desired width of the crisscross membem being simulated, and can range loom 6mm, in the case of a Tudor style window, to up to 2Bmm in the "se of a Georgian style window, However, the pablum with simulating Georgian and Tudor style lattice windows with such spacer bars is that the spacer bars act as a cold bridge which conducts heat between the inner and outer glass panels of the double glazed unit, thus significantly increasing heat loss through the double glazed unit.

An alternative to the use of spacer bars in the simulation of Georgian and Tudor style lance windows in double glazed units is to stick lead strips to one of the glass panels to sinulate the t:;eorgian or Tudor style lattice. The use of stick-on lead stops is suitable for both single and double glazed windows. However, the use of such lead strips is environmentally unfriendly, and for this reason their use is undesirable.

It is also known to simulate Georgian and Tudor style lattice windows by painting the crisscross members onto the glass panel. I lowever, in general, the simulation of such (Georgian and Tudor style lattice windows, whether single or doubled glazed' with painted criss-cro$s members tend not to look authentic. This is commonly due to the fact that the edges defined by the simulated cries cross members are feathered as a result of over-spray, and secondly, in general, the simulated criss- cross members tend to be translucent, and thereby lack authenticity.

There is therefore a need for a method Or providing simulated Georgian and Tudor style lattice windows, both double and single glazed, and there is also a need for sucl' a simulated (;eorgian or Tudor style lattice window. Further, there is a need for a method for applying a pattern to a glass panel which overcomes the problems of known methods, in particular, though not limited to the problems associated with feathered edges, and translucence of the pattem.

The present invention is directed towards providing a method for applying a pattem to a glass panel and to a glass panel having a pattern applied thereto. The invention is also directed to double glazed window unit.

According to the invention there is provided method for applying a paffem to a glass panel, the method comprising the steps of applying a surface coating composition to the glass panel to form the pattern, wherein the surface coating composition comprises a mineral based ink suitable for ceramics applications and an agglomerating agent for agglomerating the molecules of the mineral based ink together, and the surface coating composition is applied to Me glass panel by airless spraying.

Preferably, the mineral based ink is in powder form prior to mixing with the IS agglomerating agent. Advantageously, the particle see of the mineral based ink powder is relatively small. Preferably, the particle size of the mineral based ink powder is in the range of 1 micron to 10 microns. Ideally, the particle size of the mineral based ink powder is in the range of 1 micron to 7.6 microns.

In one embodiment of the invention We mineral based ink comprises 22butoxye thoxy) ethanol, lead cadmium.

In another embodiment of the invention the surface costing composition comprises a colour pigment for defining the colour of the pattem.

In a further embodiment of the invention Me agglomerating agent is a solvent, and preferably, is selected from any one or more of the following solvents: diethylens glycol monobutyl ether, propylene glycol methyl ether, - methoxy-1, 2-propanol, propylene glycol-1-rnethyl ether, methoxy-1, 2- hydroxpropane, and methyl propylene glycol. n ll

In one embodiment of the invention the SUCB coating composition is applied the airless spraying through a nozle having a bore extending therethrough which converges in one plane in a downstream direction towards an outlet of the nozle for defining the nozzle outlet as an elongated nozzle outlet.

In another embodiment of the invention the nozzle outlet defines a jet of the surface coating composition of substantially rectangular transverse cross-eection.

Preferably, the nozle outlet defines a jet of the surface coating composition of transverse cross-section having a transverse length which Is considerably greater than the transverse width of the gross-section. Advantageously, the nozzle outlet defines a jet of the surgeon coating composition of transverse cross-section of transverse length which is at least five times the transverse width of the cross" section. Ideally, the nozzle outlet defines a jet of the surface coating composition of transverse cross-section of transverse length which is at least ten times the s transverse width of the gross-section.

In a further embodiment of the invention the bore of the nozzle diverges in downstream direction in a plane at right angles to the plane in which the bore s converges for defining the nozz e outlet as an elongated nozzle outlet. Preferably, the bore of the nozzle diverges in a downstream direction at a rate which is such as to provide the jet of the surface coating composition to exit the nozzle outlet in a fan shape.

In one embodiment of the invention the bore of the nozle diverges in downstream direction at a rats which is such as to provide the jet of the surface coating oompoeXion to exit the nozle outlet in a fan shape, the fan having diverging edges whicl' diverge at an angle in the range of 5 to gO , and preferably, in the range of 10d to 904, and advantageously, in Me range of 30. to GOD, and more preferably, in the range of 30. to 60 . Ideally, the bore of the nozle diverges in a downstream direction at a rate which is such as to provide the jet of the surface coating imposition to exit the nozle outlet in a fan shape, the fan having diverging edges which diverge at an angle of approximately 30O.

JO In another embodiment of the inventan the length of the nozle outlet is at least five times greater than the width of the nozle outlet. Preferably, the length of the nozle outlet is at least ten times greater than the width of the nozzle outlet.

Advantageously, the length of the nozzle outlet is at least fifteen times greater than the width of the nozle outlet.

In one embodiment of the invention an upstream portion of the bore of the nozzle is of circular transverse oross-seobon prior to Me commencement of converging of the bore. Preferably, the circular upstream portion of the bore of the nozzle is of diameter in the range of 0.015mm to 0.25mrn, and advantageously, in the range of 0.015nnm to 017$mn.

Preferably, one of the nodule and the glass panel is moved relative to the other for applying the surface coating composition to the glass panel, the speed of relative to movement between the nozzle and the glass panel being controlled for depositing the surface coating composition on the glass panel to a desired depth.

Advantageously, the spacing of the nozzle outlet of the nozzle from the glass panel is selected to minirnise feathering of edges defining the pattern.

Is In one embodiment of the invention the spacing of the nozzle outlet from the glass panel is selected for detennining the transverse crosssectional length of the jet of the surface ocating compositor impinging on the glass panel. Preferably, the nozzle outlet is spaced apart from the glass panel a distance in the range of 1 mm to 40mm.

Advantageously, the nozzle outlet is spaced apart from the glass panel a distance in the range of 1 Omm to 40mm. Ideally, the nozzle outlet is spaced apart from the glass panel a distance of approximately 20rnm.

In one embodiment of the invention the surface coating composition is pressurised for the airless spraying thereof. Preferably, the surface coating composition is pressurized at a pressure in the range of 40 bar to 300 bar her the airless spraying thereof. Advantageously, the pressure of the surface coating composition is controlled for depositing the surface coating composition on the glass panel to a desired depth. s

In one embodiment of the invention the surface coating composition is deposited on the glass panel to a depth of at least 150 microns. Preferably' the surface coating composition is deposited on the glass panel to a depth of at least 175 microns. More preferably, the surface costing composition is deposited on the glass panel to a to depth of at least 200 microns. Advantageously, the surface coating composition is deposited on the glass panel to a depth in the range of 200 microns to 1200 microns, and ideally, the surface coating composition is deposled on the glass panel to a depth in the range of 200 microns to 250 microns.

In another embodiment of the invention the glass panel with the surface coating composition forming the pattern thereon is subjected to a high temperature heat treatment for fusing the surface coating composition forming the pattern to the glass panel. Preferably' the glass panel with the surface Coating composition forming the pattern thereon is subjected to the high temperature heat treatment at a temperature in the range of 650C to 750 C.

In one embodiment of the invention the surface coating composition forming the pattern is fused to the Glass panel during heat treatment of the glass panel for toughening thereof. g

In a further embodiment of the invention the glass panel is subjected to low temperature heat treatment for drying the surface coating composition forming the pattern thereon prior to being subjected to the high temperature heat treatment.

Preferably, the glass panel with the surface coming composition forming the pattern thereon is subjected to the low temperature heat treatment at a terr perature in the range of 90 C to 100C. Advantageously, the low temperature heat treatment of the glass panel is carried out by infrared radiation.

In one embodiment of the invention the pattern is cries-cross pattern for sitnulating a lattice type window.

In another embodiment of the invention the cries-cross pattern simulates a Georgian lance type window. Altematively, the cries cross pattern simulates a Tudor lattice is type window.

The invention also provides glass panel having a pattern applied thereto, the pattern being applied to the glass panel by the method according to Me invention' In one embodiment of the invention the glass panel is a window pane.

In another embodiment of the invention the glass panel is one of a pair of glass panels of a double glazed window unit.

flue inventor also provides a double glazed window unit having an inner glass panel and a spaced apart outer glass panel, the outer glass panel having an inner surface facing an inner surface of me inner glans panel, a pattern being applied to the inner surface of one of the inner and outer glass panels by the method according to the invention.

In one embodiment of the invention the pattern is applied to the inner surface of the outer glass panel.

to The invention will be more clearly understood from the following description of preferred embodiment thereof, which is given by way of example only, with reference to Me accompanying drawings, in which; Fig. t is a front elevational view of a double glazed window unit according to the invention, Fig. 2 is a transverse cross-sectional side elevational view of the double glazed window unit on the line loll of Fig. 1, JO Fig. is an enlarged perspective view of a portion of the double glazed window unit of Fig. 1, Fig. 4 is a perspewe Mew of a spray nozzle for use in the method according to the Invention for applying a pattem to the double glazed window unit of Fig. AL l lo. - Fig. 5 is a transverse cross-sectional side elevational view of the noble on the line V-V of Fig. 4, and Fig. 6 is a transverse cross-seional end elevational view of the nozzle on the line VI-VI of Fig. 4, Fig. 7 is a diagrammatic side elevational view of the spray nozzle of Fig. 4 to mounted relative to a glass panel of the double glazed window unit of Fig. 1 during spraying of the pattern onto the glass panel, and Fig. is a diagrammatic top plan view of the spray nozzle and glass panel of Fig. 7.

Referring to the drawings and initially to Figs. 1 to 3 thereof, there is illustrated a double glazed window unit according to the invent/on, indicated generally by the reference numeral 1. The double glazed window unit 1 composes an inner glass panel 2, and an outer glass panel 3. The inner and outer glass panels 2 and are JO spaced apart and define a cavity 4 therebetween. A spacer member B extends around the periphery of the inner and outer glass panels 2 and 3 between the respective glass panels 2 and 3 for spacing the panels 2 and 3 apart to fo To the cavils, 4, A sealing band 7 extends around the periphery of the double glazed unit 1, and sealably engages the spacer member 6 and peripheral edges 8 and of the inner and outer panels 2 and 3, respectively, for sealing the cavity 4. The inner panel 2 in this embodiment of the invention is of a heat reflective glass. Such heat rejective glasses will be well known to those skilled in the art, although it will be appreciated that it is not necessary for either of the panels to be of heat reflective glass.

A pattern 10 which in this embodiment of the invention simulates a Georgian sole lattice window is applied to an inner surface 11 of the outer panel 3 within the cavity 4 prior to asen,bling the inner and outer panels 2 and of the double glazed unit 1.

iD The method for applying the pattern 10 to the outer panel 3 comprises applying a surface coating composition. which forms the pattem, to the inner surface 11 of the outer panel 3 by airless spraying as will be described below The pattern 10 comprises a plurality of horizontal bands 14 and vertical bands 15 which simulate the lattice. In this ernhodiment of the invention since the laffioe pattern is simulating a Is (;eorgian style window, the horizontal and vertical bands 14 and 15 ate of width W of 2Qmm, and the surface coating composition is deposited to a depth d of approximately 200 microns in order to ensure that the bands are opaque. The method, as will be described below, is such as to ensure that edges 16 of the bands 14 and 15 are sharply defined. and are not feathered.

Turning now to the method according to the invention for forming the pattern 10, the surface coating composition comprises a mineral based ink in powder forth which is mixed with an a9910meratin3 agent in liquid form. A colour pigment in powder form is added to the mineral based ink as appropriate. In this embodiment of the invention the agglomerating agent is a solvent' namely. diethylene glycol monobutyl ether manufactured by Fluke Chemie GmbH of Bucks, Switzerland and supplied by Sigma Aldrich Chemie GmbH. Additionally, in this embodiment of the invention the bands 14 and 15 are white, and thus, the Velour pigment is a suitable white pigment in powder fond and is added to the mineral based ink prior to mixing with the solvent.

The mineral based ink is supplied by Johnson Matthey PLY of Stoke on Trent, England and is supplied under the name of fine white and contains 2(2-butoxye thoxy) ethanol, lead cadmium. The sizes of the particles of the mineral based Ink ranges from 1 micron to 7.6 microns. The solvent is mixed with the mineral based to ink in the proportion four parts by volume mineral based ink powder to approximately one part solvent and the mineral based ink and solvent are thoroughly mixed to form the surface coating composition for applying to the outer panel 3 by airless spraying.

Referring now to Figs. 4 to 8 the airless spraying of the surface coating composition onto the inner surface 11 of the outer panel 3 will now be described. The surface coating composition is pressurised to a pressure in the range of 40 bar to 300 bar, and typically, 140 bar, and is applied to the outer panel 3 by the airless spraying through a spray nozzle 20. The spray nozzle 20 defines a substantially rectangular shaped nozzle outlet 22 through which Me pressurised surface coating composition is applied to the outer panel 3 to form the pattern 10. A bore 23 extends through the spray nozzle 20 from an upstream end 24 to a downstream end 25 where it terminates in the nozzle outlet 22 for accomnodating the pressunsed surface coating composition therethrough. An upstream portion 27 of the bore 23 extends to a position 28, and is of circular transverse cross-sechon of diameter of

J

approximately 7 microns' A downstream portion 30 of the bore 23 converges in a plane 31 in a downstream direction from the position 28 to the nozzle outlet 22 and defines long edges 33 of the nozzle outlet 22. Additionally, the downstream portion of the bore 23 diverges in a plane 34, which is at right angles to the plane 31.

s from the position 2B, in a downstream direction to the nozzle outlet 22 for defining short edges 35 of the nozzle outlet 22. The long edges 33 and the short edges 35 define the substantially rectangular shape of the nozzle outlet 22. In this embodiment of the invention the transverse length L of the nozzle outlet 22 along the plane 34 is approximately 2mm, while the width t of the nozzle outlet 22 along the lo plane 31 is approximately 0.12mm. The angle at which the downstream portion 30 of the bore 23 diverges in the plane 34 is such as to form a jet 36 of the surface coating composition to issue from the nozzle outlet 22 wills an included fan angle a of approximately 30., see Fig. 7.

A jig (not shown) is provided for supporting the outer panel 3 horizontally with the inner surface 11 to which the pattern 10 is to be appilecl facing upwardly. The nozzle is carried on a numerically controlled carrier (also not shown)' and is directed downwardly for applying the jet 36 of the surface coating composition to the inner surface 11 of the outer panel 3 so that the jet 36 is directed vertically downwardly ho and perpendicular to the inner surface 11. The numerically controlled carrier urges the spray nozzle 20 at an appropriate speed relative to the inner surface 11 of the outer panel 3, which is set depending on the pressure to which the surface coating composition is pressurized, so that the surface coating composition is deposited to a depth d of 200 microns on the inner surface 11 for forming the bands 14 and 15.

Additionally, the spacing of the nozzle outlet Z2 above the inner surface 11 of the outer panel 3 is set at distance S. see Fig. 7, such that overspray is ninimised and in practice is eliminated for avoiding feathering of the edges 16 of the bands 14 and 15. It has been found that with a fan angle a of 30 and the pressure set at approximately 140 bar, the optimum spacing S between the nozzle outlet 22 and the inner surface 11 is approximately Comma It has also been found that if the distance S between the nozzle outlet 22 and the inner surface 11 is too close, the jet 36 on impinging against the inner surface 11 rises what is effeetvely bow wave on its leading edge, which can cause distortion of the bands, particularly when one of the lo bands, for example, one of the vertical bands 15 in crossing over an already applied horizontal band 14. If the distance 5 is too great, it has been found that over-spray commences, thus leading to feathering of the edges 16 of the bands 14 and 15.

Referring now to Fig. 8, the width W of the bands 14 and 1 S. as well as being 1s determined by the distance S between the nozzle outlet 22 and the inner surface 11 is also determined by angling the nozzle outlet 22 relative to a central axis 38 of the bands 14 and 16. so that the plane 34 defined by the nozzle 2D makes an angle with the central axis 38. In this embodiment of the inYenffon since the bands 14 and are to be of width approximately Grimm, the angle is approximately 45 , Where no it is desired to force wider band than the bands 14 and 1B, the angle is appropriately increased. To form a narrower band the angle;p is appropriately decreased It has been found that in order to form a band of approximately 6mm, which would be a typical width for bands simulating a Tudor style lattice, the nozzle IB oriented relative to the central axis 38 until the angle q, is approximately zero.

In other words, the nozle 20 is oriented relative to the central axis 38 defined by the band so that the plane 34 defined by the nozle 20 and the central axis 38 defined by the band substantially coincide with each other.

S The numerically controlled carrier (not shown) urges the spray nozle 20 at an appropriate speed relative to the inner surface 1 t of the outer panel 3 for forming the vertical bands 15 first, and when the vertical bands 15 have been fornned, the numerical controlled baffler (not shown) then similarly urges the spray nozle 20 relative to the inner surface 1 1 of the outer panel 3 for forming the horizontal hands 14.

After the bands have been formed on the outer panel 3, the outer panel 3 is subjected to a low temperature infrared radiation heat treatment for drying the surface coating Imposition forming the bands 14 and 15. The low temperature Is heat treatment is carried out at a temperature in the range of 90 C to 1 00 C for a time period of appxinately ten minutes for drying the surface coating composition.

After drying, U1e outer panel 3 is then placed In a toughening oven for toughening of the glass of the outer panel 3. The temperature of the outer panel 3 and the surface coating composition of the bands 14 and 15 is raised to a temperature in the range of 650 C to 750 C, and typically, to a temperature in the order of 700 G, which as well as toughening the glass of the outer panel 3 also causes the surface coating composition of the bands 14 and 15 to be fused with the glass of the outer panel 3, thereby effectively permanently securing the bands 14 and 16 to the outer panel 3.

The outer panel 3 is subjected to the toughening temperature of 700 C for a period of approximately one and a half minutes, upwards. Thereafter the outer panel 3 is cooled. While the rate of cooling may have an effect on the toughening of the glass, it is not orffloal from the point of view of fusing the surface coating composition of the bands 14 and 1S to the glass of the outer panel 3. Once the surface coating composition of the bands 14 and 15 and the glass have been raised to a temperature of approximately 700 C, the surface Mating composition is fused to the glass, and thereafter all that Is required is to cool the outer panel 3.

After the outer panel 3 has been cooled to room temperature, the outer panel 3 is assembled with the inner panel 2 to fornn the double glazed window unit 1.

The advantages of the invention are many. By virtue of the fad that the pattern is formed on tfe outer panel to a reasonable depth, in the order of 200 microns without feathered edges provides a window pane which effectively simulates a Georgian or Tudor style window. It is believed that the absence of feathering on the edges of the pattem is achieved by applying the surface coating composition by airless spraying.

It is believed that conventional air spraying wuld lead to feathering of the edges of the pattern as a result of air entrained in the surface Mating cornposiffon when impinging on the glass panel. It is also believed that the provision of the mineral based ink in the surface costing composition, and in particular the provision of the agglomerating agent in the surface Mating composition also assists in providing the pattern with sharp unfeathered edges. The agglomerating agent assists in binding the molecules of the mineral based ink, thereby minimising any danger of feathering of the edges. The provision of the agglomerating agent as a solvent further assists in the absence of feathering of the edges of the pattern.

By providing the mineral based ink of the type which is suitable for ceramic s applications also assists in providing the patter, with edges in which feathering is absent.

By providing the mineral based ink in powder form with particles of size in the range of 1 micron to 10 microns permits the surface coating composition to be applied to a reasonable depth in one application of the surface coating composition, Indeed, by providing the mineral based Ink to be of particles of sizes in the range from 1 micron to 7.6 Nick permits the surface coating composition to be applied to the panel to a depth of approximately 200 microns in one application. Additionally, providing the mineral based ink of the surface coating composition to be of such particle size also, it is believed. facilitates In avoiding feathering of the edges of the pattem.

While specific drying and fusing femperafures have been described, It will be readily apparent to those skilled in the art that other drying and fusing temperatures may be used' It will also be appreciated that while it is preferable it is not essential that the surface coating composition forming the pattern should be dried prior to fusing the pattern to the glass. The fusing could commence immediately the pattern had been applied to the glass. It will also be appreciated that while in this embodiment of the invention the fusing of the surface coating wmposfflon to the glass has been carried out simultaneously with toughening process for toughening the glass, the surface coating composition may be fused to the glass without necessenly toughening the , 12ss.

While the surface coating composition has been described as comprising a speFio mineral based ink, it Is envisaged that other suitable mineral based inks may be used. However, it is desirable that e mineral based ink should be suitable hr ceramics applications, and also suitable Or fusing with the glass panel. Additionally, it is desirable that the mineral based ink should be provided in powder or particulate form of particle size not less than 1 micron, and preferably, the particle size should be in the range of 1 micron to 7.6 microns.

It is also envisaged that other suitable agglomerating agents may be used besides a solvent, and where a solvent is used as the agglomerating avert, other suitable solvents besides that described may be used, for example, another suitable solvent is a solvent sold by Shell Chemicals under the trade name Methyl PROXITOL, particulars of which are set out in the Oata Sheet No. IS 3.41A of Shell Chemicals.

While the colour pigment has been described as being white colour pigment, the colour pigment selected will depend on the desired colour of the pattern to be applied to the glass panel.

Additionally, while specific construction of spray nozzle has been described, other suite'ole spray nozzles may be used, and needless to say, the surface coating composition may be pressunsed during the airless spraying to other pressures besides that described. Needless to say, thespacing of the spray nozle from the surface to which the pattern is being applied may be varied, and indeed, would be varied depending on other variables in Me airless spraying process. Additionally, it is envisaged that the nozzle may be provided in order to provide jets of the surface s coating composition issuing therefrom of included fan angles other than 30. It is also envisaged that the bore of the spray nozzle and the nozzle outlet may be of oval cross-section.

While the nozzle outlet has been described as being of length greater than its width, in certain cases, it is envisaged that the nozzle outlet may be of circular transverse gross-section, or may be of square transverse cross-section. Indeed, in certain cases, particularly when forming a Tudor type pattern, It is envisaged that the nozzle outlet may be of either circular or square transverse cross-section.

While the pattern which has been applied to the glass panel has been described as being a pattern for simulating a (Georgian sidle Isffice, any other desired pattern could be applied without departing from the scope of the invention. It will be readily apparent to those skilled in the art that a Tudor style lattice pattern could be simulated by the method according to the invention just described.

JO

While the glass panel has been described as being one of the glass panels of a double glazed unit, it will be readily apparent to those skilled in the art that the glass panel could be provided for use as a single glazed window pane, In general, it is envisaged that it is preferable to locate the pattern on the side of the glass panel 11.1 lUV. ClillO 41!1- tJO I I al ml 1 At, . which in use harms the inner side of single glazed window pane.

While the glass panel has been described as being a window pane, it will be readily apparent to those skilled in the art that pattem may be applied to any glass panel, s be it a window pane or othenuiso, and such a method and a glass panel would be within the scope of the invention.

Additionally, while the patter, has been described as being applied by a single spray nozzle, in certain cases, it is envisaged that more than one spray nozzle may be used, however, in general, it is believed desirable that for applying a band of the type used to simulate a /:;eorgian or Tudor style lattice type window, a single spray nozzle with a single nozzle outlet of the type described is preferable, and in particular, spray nozzle which outputs substantially single plane fan shaped jet of the surface coming composition. While specific dimensions of bore size and nozzle outlet size have been described, it is envisaged that a spay nozzle of different dimensions could be used.

While the depth of the surface coating composition applied to the glass panel has been described as being 200 microns, it is envisaged that the surface coating So composition may be applied to the glass panel to any desired depth, and indeed, it is envisaged that the surface coating composition may be applied to the glass panel to a depth of up to 1200 microns, and in certain cases, even to greater depot.

Claims

. l lo. =- - Claims 1. A method for applying a pattern to a glass panel,

the method comprising the steps of applying a surface coating composition to the glass panel to form the pattern, wherein the surface coating composition comprises a mineral based ink suitable for ceramics applications and an agglomerating agent for agglomerating the molecules of the mineral based ink together, and the surface costing composition is applied to the glass panel by airless spraying.

2. A method as claimed in Claim 1 in which the mineral based ink jB in powder tome prior.to mixing with the agglomerating agent.

3. A method as claimed in Claim 2 in which the particle size of the mineral based ink powder is relatively small.

4. A method as claimed in Claim 3 in which the particle size of the mineral based ink powder is in the range of 1 micron to 10 Irons.

5. A method as claimed in Claim 4 in which the particle size of the mineral based ink powder is in the range of I micron to 7.6 microns.

6. A method as claimed in any preceding claim in which the mineral based ink comprises 2(2-butoxye thoxy) ethanol, lead cadmium.

7. A rneffod as claimed in any preceding claim in which the surface coating 10. 1 lUY. =KHaO ll:J À two = ml 1 me TV. , . =- composition comprises colour pigment for defining the colour of the paffem.

B. A method as claimed' in any preceding claim in which the agglomerating l agent is a solvent. a

9. A method as claimed in Claim in which the solvent fondling the agglomerating agent is selected Tom any one or more of the following solvents: diethylene glycol monobutyl ether, propylene glycol methyl ether, nethoxy-1, 2-propanol, propylene glycol-1-methyl ether, methoxy-1, 2-hydroxpropane, and methyl propylene gIycol.

Is 1 O. A method as claimed in any preceding claim in which the surface coating composition is applied by If e airless spraying through a nozzle having a bore extending therethrough which converges in one plane in a downstream direction towards an outlet of the nozzle for defining Me nozzle outlet as an elongated nozzle outlet.

11, A method as claimed in Claim 10 in which the nozzle outlet defines a jet of the surface coating composition of substantially rectangular transverse cross section.

4= . I IV. art_ ILL ' . __. A....' . - ' 'A À - ' ' À - ' 2a 12. A method as claimed in Claim 10 or 11 in which the nozle outlet defines a jet of the surface coating conposifion of transverse cross- section having a transverse length which is considerably greater than the transverse width of the cross-section.

13. A method as claimed in any of Claims 10 to 12 in which the nozzle outlet defines a jet of the surface coating composition of transverse cross-section of transverse length which is at least five times the transverse width of me cross section.

14. A method as claimed in Claim 13 in which the nozzle outlet defines a jet of the surface coating composition of transverse cross-section of transverse length which is at least ten times the transverse width of the ross-section.

t5 15. A method as claimed In any of Claims 10 to 14 in which the bore of the nozzle diverges in a downstream direction in a plane at right angles to tile plane En which the bore converges for defining the nozle outlet as an elongated nozle outlet.

JO 16. A method as claimed in (claim 15 in Which the bore of the nozzle diverges in a downstream direction at a rate which is such as to provide the jet of the surface coating composition to exit the nozzle outlet in fan shape.

17. A method as claimed in any of Claims 15 or 16 in which the bore of me nozle diverges in a downstream dire:tion at a rate which is such as to provide the jet of the surface coating composition to exit the nozzle outlet in a In shape, the fan having diverging edges which diverge at an angle in the range of 6 to 90 .

s 18. A method as claimed in Claim 17 in which the bore of the nozle diverges in a downstream direction at a rate which is such as to provide the jet of the surface crating composition to exit the nozzle outlet in a fan shape, the fan having diverging edges which diverge at an angle in the range of 10 to got.

to 1g. A method as claimed in Claim 18 in which the bore of the nozle diverges in a downstream direction at a rate which is such as to provide the jet of the surface coating composition to exit the nozle outlet in a fan shape, the fan having diverging edges which diverge at an angle in the range of 30 to gO .

20. A method as Claimed in Claim 19 in which the bore of the nozle diverges in a downstream direction at rate which is such as to provide the jet of the surface coating composition to exit the nodule outlet in a fan shape, the fen having diverging edges which diverge at an angle in the range of 30 to 60.

21. A medhod as claimed in Claim 20 in which the bore of the nozle diverges in a downstream direction at a rate which is such as to provide the jet of the surface coating composition to exit the nozle outlet in a fan shape, the fan having cliverging edges whim diverge at an angle of approximately 300.

22. A method as claimed in any of Claims 10 to 21 in Which the length of the nozle outlet is at least five times greater than the width of the nozzle outlet. l

23. A method as claimed in Claim 22 in which the length of the nozzle outlet is at least ten times greater than the width of Me nozzle outlet.

24. A method as claimed in Claim 23 in which the length of the nozzle outlet is at least fifteen times greater than the width of the nozzle outlet.

to 25. A method as claimed in any of Claims 10 to 24 in which an upstream portion of the bore of the nozle is of circular transverse cross-section prior to the commencement of converging of the bore.

26. A method as claimed in Claim 25 in which the circular upstream portion of the bore of the nozzle is of diameter in the range of 0.015mm to 025mm.

27. A method as claimed in Claim 26 in which the circular upstream portion of the bore of the nozzle is of diameter in the range of 0.015mm to 0.175mm.

JO 20. A method as claimed in any of Cisim5 10 to 27 in which one of the nozzle and the glass panel is moved relative to the ocher for applying the surface coating composition to the glass panel. the speed of relative movement between the nozzle and the glass panel being controlled for depositing the surface coating compo$itlon on the glass panel to a desired depth.

2g. A method as claimed in any of Claims 10 to 28 in which the spacing of the nozzle outlet of the nozzle from the glass panel is selected to minimise feathering of edges defining the pattem.

30. A method as claimed in any of Claims 10 to 23 In which the spacing of the nozzle gullet from the glass panel is selected for determining the transverse cross sectional length of the jet of the surface coating composition impinging on the glass panel.

31. A method as claimed in any of Claims 10 to 30 in which the nozzle outlet is spaced apart from the glass panel a distance in the range of 1 mm to 40mm.

32. A method as claimed in Claim 31 in which the nozzle outlet is spaced apart from the glass panel a distance in the range of lOmm to 40rnm.

33. A method as claimed in Claim 32 in which the nozzle outlet is spaced apart from the glass panel a distance of approximately ZOrnm.

So 34. A method as claimed in any preceding claim in which the surface coating composition is pressurized for the airless spraying thereof.

35. A method as claimed in Claim 34 in which Me surface coating composition is pressurised at a pressure in the range of 40 bar to 300 bar for the airless spraying thereof.

36. A method as claimed in Claim 34 or 35 in which the pressure of the subrace coating composition is controlled for depositing the surface coating composition on the glass panel to desired depth.

37. A method as claimed in any preceding claim in which the surface coating composition is deposited on the glass panel to a depth of at least 150 microns.

lo 38. A method as claimed in Claim 37 in Which the surface coating composition is deposited on the glass panel to a depth of at least 1 7S microns.

30. method as claimed in Claim 38 in which the surface coating composition is deposited on the glass panel to a depth of at least 200 microns.

IS

40. A method as claimed in Claim 39 in which the surface coating composition is deposited on the glass panel to a depth in the range of 200 microns to 1200 microns.

41. A method as claimed in Claim 40 in which the surface coating composition is To deposited on the glass panel to a depth in the range of 200 microns to 250 microns.

42. A method as claimed in any preceding claim in which the glass panel with the surface coating composition Coning the pattern thereon is subjected to a high temperature heat treatment for fusing the surface coating composition forming the fig pattern to the glass panel.

43. A method as claimed in Claim 42 in which the glass panel with the surface coating composition forming the pattem thereon is subjected to the high temperature s heat treatment at a temperature in the range of 650 C to 750 G.

At. A method as claimed in any preceding claim in which the surface coating composition forming the pattern is fused to the glass panel during heat treatment of the glass panel fortoughening thereof.

45. A method as claimed in any of Claims 42 to 44 in which the glass panel is subjected to a low temperature heat treatment for drying the surface coating composition forming the pattern thereon prior to being subjected to the high temperature heat treatment.

46. A method an claimed in Claim 45 in which the glass panel with the surface coating composition forming the pattern thereon is subjected to the low temperature heat treatment at a temperature in the range of GO6C to 100 .

To 47. method as claimed in Claim 45 or 46 in which the low temperature heat treatment of the glass panel is carried out by infrared radiation.

48. A method as claimed in any preceding claim in which the pattern is a criss- cross pattern for simulating a lattice type window. À 2g

49. method as claimed in Claim 48 in which the crisscross pattern simulates a Georgian lattice type window.

50. A method as claimed in Claim 48 in which the cries-cross pattern simulates a Tudor lattice type window.

51. A method for applying a pattern to glass panel, the method being substantially as described herein with reference to and as illustrated in the accompanying drawings.

52. A glass panel having a pattern applied thereto, the pattem being appiled to the glass panel by the method as claimed in any preceding cluing, Is 53. A glass panel as claimed in Claim 62 in which the glass panel is a window pane.

54. glass panel as claimed in Claim 52 or 63 in which the glass panel is one of a pair of glass panels of a double glazed window unit.

55. A glass panel substanffally as described herein With reference to and as illustrated in the accompanying drawings.

56. A double glazed window unit having an inner glass panel and a spaced apart outer glass panel. the outer glass panel having an inner surface facing an inner surface of the inner glass panel, a paffem being applied to the inner surface of one of the inner and outer glass panels by the method as claimed In any of Claims 1 to S1, 57. A double glazed window unit as claimed in Claim 56 in which the pattern is applied to the inner surface of the outer glass panel.

58. A double glazed window unit substantially as described herein with reference to to and as illustrated in the accompanying drawings.