Silicon coating on glass

COMPLETE SPECIFICATION (ORIGINAL)

FOR OFFICE USE

Short Title:

Int. Cl.:

Form 10

Regulation

13(2)

Application Number:

Lodged :

Complete Specfication - Lodged: Accepted : Lapsed : Published :

' amendment 1?°?^{tains the}Section 49 _{a nr)}⁷⁷¹³⁰⁶ kinder Printing ^3ndjscoect for

C€·'· e « c c <

C f c e c <

c e c c < t t t:

t t« r r e r r t t t t t i t text

Priority:

Related Art:

• TO BE COMPLETED BY APPLICANT

<img file="AU582178B2_D0001.tif" />

Name of Applicant:

Address of Applicant:

Actual Inventor:

Address for Service:

PILKINGTON BROTHERS P.L.C.

Prescot Road, St. Helens, Merseyside WA 10 3TT, England

DAVID ANTHONY PORTER

ARTHUR S. CAVE &amp; CO., Patent and Trade Mark

Attorneys, 1 Alfred Street, Sydney, New South Wales, Australia, 2000.

Complete Specification for the invention entitled:

COATED PRODUCTS

The following statement is a full description of this invention, including the best method of performing it known to me:- ’ .......

ASC 48 &amp; 49

<img file="AU582178B2_D0002.tif" />

I

-la COATED PRODUCTS

The invention relates to the production and use of glass with a surface coating which provides a barrier to the migration of alkali

<img file="AU582178B2_D0003.tif" />

metal ions out of the glass surface, and to products incorporating such coated glass.

It is known that certain surface coatings on

<td> (</td><td> glass deteriorate</td><td> as a</td><td> result of</td><td> m i</td><td> gration of</td>

<td></td><td> alkali metal ions</td><td> out</td><td> of the gla</td><td> s s</td><td> surface</td>

<td> • «· ’ ί</td><td> 10 into the coating.</td><td> For</td><td> example, U</td><td> . K .</td><td> Patent</td>

<td> c t</td><td> Specification 705</td><td> 9 3 4</td><td> describes</td><td> the</td><td> appearance</td>

c c c t _£ of haze in a transparent electro-conductive t t t c c r t coating on soda lime silica glass. The haze fit!

may be reduced by removing alkali metal ions from the glass surface before applying the

<img file="AU582178B2_D0004.tif" />

ε e c c c f t t c r c C f. € ζ r f i ft

C C 1

C r ?

electroconductive coating, or by applying an intermediate film, for example of silica or titanium oxide, before the electroconductive coating is applied. The silica films are prepared either by applying a solution of silicon tetrachloride or tetrabromide or of silico-chloroform in a volatile non-aqueous solution, to the glass, and exposing to the atmosphere until the coating is dry and then rub-bing until the coating is bright, or by dipping a glass sheet in a solution of a .,,s

I

<img file="AU582178B2_D0005.tif" />

partially hydrolysed example ethyl ortho

European Patent Spec is similarly concern silica ac silicate, if ication and

EP ed with the of electroconductive silica glass diffusing with over lyi metal. It refer electroconducti transparency , resistance durability diffusion .

of liquid and layer to

It ester, for drying.

071 865 A3 deterioration tings on oda lime of alkali metal ion urface and interact!

ng sensitive to alkali whi turbidity in the layer reduction also crystal refer reduction electric n physic display oc h em i c a1 s eq u e no to the devices e1ectrochromic devices and of such deteriorati amorphous silicon photovoltaic cells as a result of the diffusion of alkali metal ions from a glass substrate. Such devices generally include electroconductive layers, for example of indium tin oxide, on the glass, but

EP 0 071 865 A3 refers to effects (additional to any direct effect of the alkali metal ions on the electroconductive layer) which result layers overlying the electroconductive from interaction of the alkali metal ions with

V

V

<td> EP 0 071</td><td> 8 65</td><td> A3 proposes to prevent</td><td> the</td>

<td> diffusion</td><td> of</td><td> alkali metal ions from</td><td> a glass</td>

<td> substrate</td><td> by</td><td> use of a barrier layer</td><td> of silicon</td>

<td colspan="2"> oxide which</td><td> contains hydrogen bonded</td><td> 10</td>

<td> silicon .</td><td> The</td><td colspan="2"> barrier layer may be prepared by</td>

vacuum vapour deposition, sputtering, ion plating, sol/gel methods or by CVD i.e. chemical vapour deposition. In the CVD methods described, silicon oxide layers are deposited &lt; r t I { !

t t c r

C ».

S ί « r t C ΐ . r €

t t r c « t t t « « e £ r s r e on glass substrates under oxidising conditions at temperatures of from 300°C to 550°C from oxygen gas and monosilane gas (S1H4) in ratios of 0 2^: S i H 4 of 10:1 to 60:1.

U.K. Patent Specification 2 031 756B discloses the use of layers of metal oxide, including t it &lt;c « « ί f

C ‘:

ct

C ‘ (

t L

C ·“ silicon oxide, as colour damping layers to reduce the irridescent reflection colours exhibited by infra red reflecting coatings of semiconductor metal oxides on glass. The semiconductor metal oxide may be a fluorine doped tin oxide, and the specification refers to the known effect of amorphous silicon oxide layers in ions from overlying inhibiting diffusion of alkali metal the glass thereby avoiding haze tin oxide layer. The colour damping f 0 rma t i on on. subsequent deposition of an layers used in accordance with U.K. Patent

<img file="AU582178B2_D0006.tif" />

Specification 2 031 756B preferably have a refractive index of 1.7 to 1.8 and are from 64 to 80nm thick. Layers containing silicon oxide may be prepared by chemical vapour deposition on hot glass at

300° to 5 00 °C using silane in the presence of an oxidising gas.

.K. Patent Specification 1 507 465 describes process for applying a reflective coating of to flat glass to provide a solar ter:

ε ε

r. v c .

r r t t r r * * c s e t t € t t C t « r t €

« &lt; £ « control s ilver applied glass with an aesthetically pleasing ion colour. The coating by releasing silane gas into a zone opening towards the glass surface hot , and maintaining ηοn-oxidising conditions in the said hot zone, so that the silane pyrolyses « &lt; t r « r £ ^s ε « ζ · (

C t ¹c t t 1 1 depositing the reflecting silicon coating on the glass surface. U.K. Patent Specification

573 154 describes an improvement in the

5ΌΊ L-bS process of—i—54)-?—6-4-5-/for producing reflecting solar control glass; in the improved process, a gaseous electron donating compound, for example ethylene, is added to the silane containing gas and leads to an unexpected improvement in the resistance of the coated

<img file="AU582178B2_D0007.tif" />

glass to attack by external alkali. The ratio of electron donating compound to silane is generally 0.1 to 2.0, and preferably 0.2 to

<img file="AU582178B2_D0008.tif" />

although the specification does refer to the use of a ratio greater than . 5 , for example 5, to produce an alkali resistant silicon coating with very good abrasion resistance but without the high reflectivity to visible light obtained in the absence of the electron donating compound. The coatings

<img file="AU582178B2_D0009.tif" />

£ ί^- &lt;· · r t 4 ί i.

t t

C &lt;¢:t £

1t « r ; r ®c r t tc « « t € t t &lt; « I are applied to architectural glass, and the examples describe the application of the coatings to 6 mm soda lime silica float glass and to rolled glass. Coatings obtained using ethylene as the electron-donating compound were analysed and it was found that, although they were prepared under non-oxidising conditions, they contained some oxygen.

&lt; « Γ t t r ε r ·C £ f &lt; · (

£ 1 · t € i t

The applicants have found that thin transparent coatings produced in the presence of a high proportion of electron donating compound as described in U.K. Patent from the glass and are surprisingly effective as barriers to the migration coated glasses are useful of alkali metal substrates for overlying layers (whether lying directly on the barrier layer or over an intermediate layer) sensitive to alkali metal ions.

ions from the glass surface.

The resultant it

According to provided a me alkali alkali which glass the present invention there is of reducing diffusion metal metal method ions ions r om compr a glass containi an overlying lay providin ng between the and the overlying barrier applied of lay er a transparent by glass ting containi pyrolysis of e d in gaseous elec that the e above

0 0 °C ga iron donating and oxygen pyrolysed the presence compound

¢.

r c c

C T i e c r ' C C £ e

- c whereby oxygen fr with silicon to coating up to

C ί f t c

&lt; I &lt;

surface.

The expression is used herei when thick light

The i coati

II om form nm present , result n ven ng a in which the glass is incorporated a transparent barrier thick on the transparent to refer to clear float bar r coati gl a s n the ion of coated further gl a s at least provides glass n gs coating which up to 6 having mm a method of glass containing alkali metal ions a silane gas is pyrolysed on the glass surface above 6 00 °C in the presence of a gaseous electron donati ng compound , whereby oxygen from the glass is incorporated with

S'

·.·

Jr .

silicon to form on transparent containin sensitive ions over

The the glass surface from the barrier silicon c oa and the d i f f the glass coated gla layer sensitive ting up oxy gen , ion of to 5 0 and a alkali subsequently surface .

the diffusi n m thick layer metal appli ed of alkali metal ions transmi tti which the from the ng layer glass may be a of doped metal light oxide .

on donating compounds compounds contain, either in bonds ons, electrons which can structure of su as lone be donated molecules c ompou nds bonds are pair into itable acceptor

Examp les of which contai unsaturated olefins (alkenes) and for example ethylene, dif1uoroethy1ene , and aromatic hydrocarbons electron donating n the donor electrons in hydrocarbons, especially acetylenes butadiene, acetylene (alkynes), pentene, (C 2 H 2) r and for example benzene and xylene. Examples of electron donating compounds which contain their donor electrons in lone pairs are ethers, amines, aldehydes, ketones, alcohols, hydrides of nitrogen carbon monoxide and carbon dioxide. It preferred, for reasons of convenience, to use st s

electron donating compounds which are gaseous under ambient conditions, but other electron

The us found in the with s g compounds can be used without undue ty provided they have vapour the result least 5 KPa at electron do na t i compound is ma η n e r no understood, incorporati transparent

Although the is believed of oxygen from the glass from the barrier i η vo 1 coa ve i1 a n e to form the electron donati ng c ting on is not u adsorpti the glass nders tood on of the ompound on the glass s u r f ac

Thus, although the py rolysis may be ca r r i ed out i the absence of any oxygen containing gases transparen t coati g con ta i n i n g s i 1 i c and oxygen derived from ο n the glass is

<td></td><td> obtained</td><td> and</td><td> not</td><td colspan="2"> a reflecting silicon</td>

<td> 20</td><td> coating.</td><td></td><td></td><td></td><td></td>

<td></td><td> The rate</td><td> of</td><td> mi gr a</td><td> t i ο n</td><td> of oxygen containing</td>

<td></td><td> species f</td><td> r om</td><td> the</td><td colspan="2"> glass depends on the glass</td>

<td></td><td> temperatu</td><td> re ,</td><td> and</td><td> the</td><td> coating is therefore</td>

<td></td><td> depos i ted</td><td> at</td><td colspan="2"> a glass</td><td> temperature above 600°</td>

<td> 25</td><td> in order</td><td> to</td><td colspan="2"> increase</td><td> the availability of</td>

oxygen-containing species from the glass

C

<img file="AU582178B2_D0010.tif" />

e&gt;

Η

<img file="AU582178B2_D0011.tif" />

The oxygen in the transparent barrier coatings

<td> is not necessarily</td><td> all</td><td> derived from</td><td> the glass</td>

<td> but may be derived</td><td> i n</td><td> part from the</td><td> electron</td>

<td> donating compound</td><td> and</td><td> some further</td><td> oxidation</td>

<td> may occur when the</td><td> c o a</td><td> ted glass is</td><td> exposed to</td>

<td> atmospheric oxygen</td><td colspan="3"> after the coating</td>

<td> operation . However</td><td> , i t</td><td> is preferred</td><td> to use</td>

electron donating compounds which are free from oxygen or which, although they contain some oxygen, are generally regarded as reducing, for example carbon monoxide and alcohols. In general, it i. s preferred to avoid the use of oxygen-cοntaining gases which react with silane before it reaches the hot glass surface with the deposition of powdery deposits of silicon oxides. In particular, the

<td> presence</td><td> of molecular</td><td> oxygen</td><td> should</td><td> b e</td><td> avoided.</td>

<td colspan="2"> In a preferred aspect</td><td> of the</td><td> inventi</td><td> ο n</td><td> , the</td>

<td> electron</td><td colspan="2"> donating compound is</td><td> oxygen</td><td> f</td><td> r e e .</td>

Because the amount of oxygen containing

Examples of oxygen free electron donating compounds which may be used are unsaturated hydrocarbons, aromatic hydrocarbons, amines and hydrides of nitrogen.

species available from the glass is limited, the transparent coatings produced using

<img file="AU582178B2_D0012.tif" />

- 10 electron donating compounds which are free from oxygen are of limited thickness, and the invention is particularly concerned with transparent barrier coatings containing silicon and oxygen and having a thickness up to 5 0 nm . '

C j ' C v i* Cf t C ί )i «

C * c r c

The proportion of electron donating compound to silane required to produce a transparent coating will depend on the particular electron donating compound used, and can readily be determined by simple trial in which the proportion of electron donating compound to silane is increased until a satisfactory light transmitting coating is produced. Suitable

<img file="AU582178B2_D0013.tif" />

€ * c j a € r at

I

c. t ' ' ?

C C ·.15 proportions of gaseous electron donating compound:si1 ane will generally be in the range

0.5:1 to 15:1 by volume. When using an olefin, it has been found that proportions of olefin : silane in the range 3:1 to 10:1 give the best results.

The use of excessive proportions of certain oxygen free electron donating compounds to silane has been found to inhibit the formation particular proportion which constitutes an of any coating and should be avoided. The

<img file="AU582178B2_D0014.tif" />

excess will depend on the particular electron donating compound used, but can readily be determined by simple trial.

Because the transparent barrier layers used in the present invention may be prepared in the absence of free oxygen and compounds generally regarded as coating may glass as it oxidising agents, the barrier applied to a ribbon of float advanced over the molten metal bath on which it is formed without undue risk of oxidising the molten metal. It is preferably applied at a glass temperature in the range 600° to 7 5 0 °C and especially at a glass temperature in the range 600° to 700°C.

The barrier coatings may be applied using the laminar flow process and apparatus described in U.K. Patent Specification 1,507,465.

« c c e t &lt; e t et ci c c sc

Preferably, the silane used is monosilane, and it is used in admixture with an inert gas, for

C Cf £ e

C &lt; ( example nitrogen.

The coatings used in the invention are highly effective as barriers to the migration of alkali metal ions, with coatings as thi n as nm giving excellent effects, while even thinner coatings, e.g. 5 nm or even thinner, have useful barrier properties.

For some applications, a high degree of transparency is required and coatings which,

<td></td><td> on clear float glass</td><td> up</td><td> to</td><td> 6 mm</td><td> thick, provide</td>

<td></td><td> a light transmission</td><td> of</td><td> a t</td><td> least</td><td> 8 0 % are</td>

<td> 5</td><td> preferred. In additi</td><td> on ,</td><td> for</td><td> some</td><td> applications ,</td>

<td></td><td> it is desirable that</td><td> the</td><td> b a</td><td> r r i e r</td><td> have good</td>

have found

W e resistanc e to external alkali.

ft.

that the electron coatings prepared in the donating compounds which contain significant quantities of presence of are organic carbon and have good resistance to attack by external ί ί c c c

C € t C e

»·. &lt;

c t«

¢. c

C fc ret c 11 c r t c c « t t ti t c

C ί c t alkali .

After deposition of the barrier coating, a layer sensitive to diffusion of alkali metal ions from the glass is applied over the barrier coating. Such a layer may be applied in known manner, e by sputtering, chemical ( st c c t &lt;

€ C t t t t c c c vapour deposition, or spraying of reactants in liquid or solid form onto the coated surface.

The barrier coated glasses are used in accordance with the invention to reduce the e c c o c c c c c c c t cc ί diffusion of alkali metal ions from a glass containing alkali metal ions into an overlying an intermediate layer. The overlying layer may layer sensitive to alkali metal ions which may be directly on the barrier layer or over be a light transmitting electroconductive metal oxide coating. Such coatings, as used commerc ially, generally have a resistivity of less than 500 applications

e.g. less tha ohms requi per re a ohms square; some much lower resistivity per square and employ coatings that have as low a resistivity as possible consistent with satisfactory optical

3' properti es. According to EP 0 071 865 referred to above, such coatings are deterioration on diffusion of alkali prone to metal ions from an underlying glass substrate with loss of light transmission and reduction in c ttt

C £ € f it t c « t e £ fit electroconductivity. Examples of light transmitting electroconductive metal oxides are doped metal oxides and include indium oxide doped with tin, which is usually deposited by sputtering, and doped tin oxides, etc c c er ct c « Ct especially f1uorine-doped tin oxide, which may be deposited by sputtering, or by chemical vapour deposition, or by solution or powder spray. The thickness of the electroconductive layer will depend on the conductivity required, but will commonly be in the range

0 nm to 15 0 0 nm.

« · • · · ·

A · • · •« · · •· A

A ·· •· A · • · · A •

• β A ·

(..

• at • · A A * •

A A

A

<img file="AU582178B2_D0015.tif" />

<img file="AU582178B2_D0016.tif" />

Transparent electroconductive metal oxides, for example infra coati into doped indium oxide and doped tin oxide , usually reflect red and so are useful as gs ndow glass reflect heat back

When used infra red reflecting layer uc h coati gs generally have

0 0

Thus thicknesses nm .

accord’ng invention , flat glass containing there c omp r the range further provided g a gl a s ka 1 i metal ions

200 nm to aspect of the lectroconductive ubstrate oated with a transparent containing silane gas the presenc bar ili on a e of compound whereby incorporated transparent surface, and layer having gl a with bar r i layer up nd oxy gen s surface gaseous oxygen f r silicon er coatin nm thick by pyrolys i above 600’C electron donati om the glass to form g on the electroconductive resistivity of less ohms per square elec troconducti light doped the gl a s metal than s of ng oxide

500 over the ve metal transmitting layer

A metal oxi de .

barrier layer.

oxide layer may

The be a and may be of a

<img file="AU582178B2_D0017.tif" />

<td> Similarly ,</td><td> the invention provides</td><td> infra</td><td> red</td>

<td> reflecting</td><td> flat glass comprising a</td><td> glass</td><td></td>

<td> substrate</td><td> containing alkali metal</td><td> ions,</td><td> coated</td>

with a transparent barrier layer up to 50 nm

<td> 5</td><td> thick containin</td><td colspan="2"> g silicon and oxygen by</td>

<td></td><td> pyrolysis of a</td><td> silane gas on a</td><td> glass surface</td>

<td></td><td> above 6 0 0 ° C in</td><td> the presence of</td><td> a gaseous</td>

electron donating compound whereby oxygen from the glass is incorporated with silicon to form 10 the transparent barrier coating on the glass surface and a light transmitting, infra red reflecting doped metal oxide layer over the barrier layer.

The barrier coated glasses have additional advantages when used in more complex systems, e.g. as substrates for electroconductive metal oxide coatings in liquid crystal display devices. Such devices may comprise two opposed electroconductive layers with a liquid crystal material between the layers, and an alignment layer over each said electroconductive layer;

<img file="AU582178B2_D0018.tif" />

€ It t l Γ o &lt; c r « tt£ €

at least one of the electroconductive layers being a light transmitting layer supported on a glass surface with a barrier layer between the electroconductive layer and the glass. In such cases, the barrier layer not only protects the electroconductive metal oxide

<img file="AU582178B2_D0019.tif" />

<img file="AU582178B2_D0020.tif" />

I I;

ilayer from direct attack by alkali metal ions from the glass, but also prevents undesirable electrochemical reactions resulting from diffusion of alkali metal ions through the e1ectroconductive metal oxide layer into the liquid crystal material.

<td> The</td><td> glass used</td><td> i n</td><td> liquid</td><td> crystal</td><td colspan="2"> displays is</td>

<td> very</td><td colspan="2"> thin, usually</td><td colspan="2"> not more than</td><td> 2 mm</td><td> thick</td>

<td> and</td><td> preferably</td><td> les</td><td> s than</td><td> 1 . 5 mm</td><td> thick .</td><td> Thus</td>

<td> 10 the</td><td> invention</td><td colspan="3"> further provides,</td><td> as new</td><td></td>

p r oduc t s ,

<td> glass up</td><td> to</td><td> 2</td><td> mm</td><td colspan="2"> thick with a transparent</td><td></td>

<td> barrier</td><td colspan="2"> coati</td><td> ng</td><td> up to 50 nm thic</td><td> k containi</td><td> ng</td>

<td> silicon</td><td> and</td><td colspan="3"> oxygen deposited by</td><td> pyrolysis</td><td> o f</td>

<td> 15 a silane</td><td> gas</td><td></td><td> i n</td><td> the presence of</td><td> a gaseous</td><td></td>

electron donating compound whereby oxygen from the glass is incorporated with silicon to form the transparent barrier coating on the glass surface ,

0 and a liquid crystal display device comprising two opposed electroconductive layers, with a liquid crystal material between the layers and an alignment layer over each said electroconductive layer in contact with the tee c e « c c e «Ct t

C « t tt r e t ( ·

CC.C ¹ ε r &lt; t &lt; f j t r € tie et t c t tf « €

io liquid crystal material of said electroconducti on a glass substrate up containing alkali electroconductive transparent barri to metal layer containing silicon glass by pyrolysi of a gaseous elec whereby oxygen with silicon to coating on the

The transparent also useful as amorphous which layers mm ions and layer up and om and the least one supported thick , between said glass, a nm thick oxygen silane the g1a s form bar the t r a n surface.

deposited on the er coated the presence compound s incorporated parent barrier glasses are sparent outer layer silicon solar cells, migration of alkali metal ions s in where out of the glass surface into the amorphous reduc es the efficiency of silicon the cell .

The barri inventi because layers , coatings used in the present are highly effective in controlling of they they transmission alkali metal ions. Moreover, are may effective i n very provi de thin barrier ecause the coatings incorporate c oa t e.d glass o f high visible light oxygen from the glass, it is not necessary to

<img file="AU582178B2_D0021.tif" />

use strongly oxidising conditions for their production, and they are suitable for commercial production on-line on a ribbon of float glass as it passes over the float bath.

Transparent barrier coatings as used in the present invention prepared using ethylene were examined by infra-red spectroscopy for the presence of Si-H bonds, but no infra-red absorptions corresponding to Si-H bonds could 10 be detec ted .

<img file="AU582178B2_D0022.tif" />

The invention is illustrated but not limited by the following Examples. Unless otherwise stated, gas volumes were measured under ambient conditions i.e. approximately 20°C and 1 atmosphere pressure.

Example s 1-4

<td> A</td><td> ribbon</td><td> of 6</td><td> mm float glass</td><td> was coated</td><td> over a</td>

<td> 3</td><td> metre</td><td> width</td><td> with a barrier</td><td> coating as</td><td> i t</td>

<td colspan="2"> advanced</td><td> over</td><td> the float bath</td><td> by passing</td><td> a</td>

mixture of 50

1itres/minute of 10% by volume monosilane in 90% by volume nitrogen and 10 1itres/minute of ethylene parallel to the glass surface under laminar flow conditions as described in U.K. Patent Specification

1,507,996. The temperature of the glass at the coating station was 625°C and the lehr speed of the glass ribbon was 370 metres/hour. The flow rate of ethylene was then increased a.,.' barrier coatings applied at ethylene flow rates of 20, 30, 40 and 50 litres/minute.

The ethy1ene:si1 ane ratios used in the coating gases and the results of measurements on the coatings produced are set out in

Table 1 .

The use of ethylene results in a reduction in light reflection and a rapid increase in light transmission up to an ethylenecsilane ratio of about 4:1. Further increase in the ^ru» ethylene:silane ratio results in a further but

t. t r t ₄ , ' * slower increase in light transmission of the v 111

S ^r 15 product.

The effectiveness of the coatings as barriers to the migration of alkali metal ions from the c c _t‘_(t glass surface was determined as described e t&lt; below.

c &lt;

Ct:

Two samples of the coated glass, each 10 cm o r r e t £ rot r square, were cut and clamped together with an annular silicone rubber ring of internal diameter 8 cm between them to form a cylindrical cell with its walls defined by the coated surface of the glass and the inner

<img file="AU582178B2_D0023.tif" />

TABLE 1

<td> Example</td><td> Mole ratio ethylene/silane</td><td> Coating Thickness (nm)</td><td> Light Transmission* %</td><td> Light Reflection* %</td><td> Alkali metal ion extraction microgram/dm^</td>

<td> Comparative</td><td> 2</td><td> 50</td><td> 67.3</td><td> 24.5</td><td> 9</td>

<td> 1</td><td> 4</td><td> 50</td><td> 81.3</td><td> 12.6</td><td> 18</td>

<td> 2</td><td> 6</td><td> 32</td><td> 82.5</td><td> 11.0</td><td> 22</td>

<td> 3</td><td> 8</td><td> 30</td><td> 83.0</td><td> 9.5</td><td> 26</td>

<td> 4</td><td> 10</td><td> 17</td><td> 84.4</td><td> 8.9</td><td> 26</td>

* determined using a C.I.E. Illuminant C source on the side of the glass remote fran the coating.

<img file="AU582178B2_D0024.tif" />

surface of the silicone rubber ring. The cell was filled with de-ionised water through a hole in the rubber ring, the hole sealed and the sealed cell immersed in a water bath at

96°C for 48 hours. The solution was removed and analysed for sodium by flame emission spectroscopy. The sodium determined and expressed per square decimetre of extract was as micrograms of N a 2 0 glass exposed to the

<td></td><td> 10</td><td> water in the</td><td> cell.</td><td></td>

<td>^β C f .» c</td><td></td><td> The test was</td><td> also carried out on</td><td> a number of</td>

<td> ri ie t 4 r t</td><td></td><td> c omme r c i a 11y</td><td> available soda lime</td><td> silica</td>

<td> l 11 t c « e - &gt; =-t t</td><td></td><td> glasses with</td><td> silica ion-blocking</td><td> surface</td>

<td> r it J t 1 &lt; H «</td><td></td><td> layers. The</td><td colspan="2"> results obtained ranged from</td>

<td> « &lt; t t h t r</td><td> 15</td><td> 60 microgram</td><td colspan="2"> Na20/dm² to over 1000 microgram</td>

Na20/dm2. An uncoated commercially available glass, nominally alkali free, was also tested and a result of 13 microgram N-a20/dm²obtained .

It will be seen that the coated glass used in

<img file="AU582178B2_D0025.tif" />

I *

J * t t I t t £

&lt;

the invention compares favourably with commercially available nominally alkali free glasses and coated glasses which, it is believed, are prepared by off-line methods not readily adaptable for the on-line coating of float glass.

The product of Example 3 was analysed by ESCA (electron spectroscopy for chemical analysis) .

In this technique, the surface to be analysed is irradiated with X-rays, and the elements present in the surface are characterised and quantified by examining the energy spectrum of the primary electrons emitted from the surface .

The surface atomic layers are then removed by argon etching to expose sub-surface atoms which are then characterised and c

« £ - c c ε &lt; £ &lt; tft δ « «t c11 t tt e c ct e t **

111 * t tttt quantified as described above. The etching and analysis steps are repeated to build up a profile of the composition of the surface layers to a depth in excess of the thickness of the coating.

The results obtained for the pr oduc t of « «&lt;

• · e • « &lt; t κ i &lt; t l

Example 3 are set out below.

<td></td><td> Etch time (seconds)</td><td> 0</td><td> 300</td><td> 600</td><td> 900</td><td> 1200</td><td> 1500</td>

<td></td><td> Atomic « silicon</td><td> 20</td><td> 35</td><td> 36</td><td> 37</td><td> 37</td><td> 35</td>

<td> 20</td><td> Atomic % oxygen</td><td> 31</td><td> 45</td><td> 39</td><td> 35.5</td><td> 37</td><td> 43</td>

<td></td><td> Atomic % carbon</td><td> 45.5</td><td> 17</td><td> 22</td><td> 24</td><td> 20</td><td> 15</td>

<td></td><td> The coating</td><td colspan="2"> is found</td><td> to</td><td colspan="2"> contain</td><td> silicon ,</td>

<td></td><td> oxygen and</td><td> carbon</td><td colspan="2"> . The</td><td> ratio</td><td> o f</td><td> oxygen : silicon</td>

3:2. It falls to about 1:1 after

900 seconds etch and subsequently increases. The

<img file="AU582178B2_D0026.tif" />

at the surface of the coating is approximately *

.· s\

<img file="AU582178B2_D0027.tif" />

- 2 3 concentration of carbon at the surface is 45%, and it varies around 20% through the thickness of the coating.

Examples 5 and 6

A ribbon of 2 mm float glass was coated with a transparent barrier coating of silicon and oxygen as it advanced over the float bath by passing a mixture of monosilane, nitrogen and ethylene parallel to the glass surface under laminar flow conditions as described in U.K. Patent Specification 1,507,996. The ' '' temperature of the glass at the coating _cr' station was 6 6 0 °C and the lehr speed of the

C £ ε € glass ribbon was 1 0 3 0 metres/hour.

The gas flows and properties of the products obtained are set out in Table 2.

<img file="AU582178B2_D0028.tif" />

V ft &lt; » I tit i ft ft &lt; ft ft t

The coatings produced had useful ion blocking properties. The light reflection increased with increasing ethylenezsilane ratio giving a light transmiusion of 84.9% at a ratio of 3.3:1. Calculations indicated that 1 mm glass with a similar coating would have a light transmission of 85.4%, compared with a transmission of 91.4% for uncoated 1 mm glass.

<img file="AU582178B2_D0029.tif" />

TABLE 2

<td> Example</td><td> Cone, of silane in nitrogen (% by volume)</td><td> Rate of flow of silane in nitrogen (litre/minute/metre width of glass)</td><td> Rate of flow of ethylene (litre/minute/metre width of glass)</td><td> Molar ratio ethylene:silane</td><td> Light transmission* O' Λ</td><td> Light Reflection* O' Λ</td><td> Alkali metal ion + extraction microgram/dm^</td>

<td> 5</td><td> 15</td><td> 30</td><td> 10</td><td> 2.2:1</td><td> 76.5</td><td> 18.5</td><td> 4</td>

<td> 6</td><td> 15</td><td> 30</td><td> 15</td><td> 3.3:1</td><td> 84.9</td><td> 12.5</td><td> 18</td>

* determined using a C.I.E. Illuminant C source on the side of the glass remote from the coating.

+ determined as described with reference to Examples 1 to 4.

<img file="AU582178B2_D0030.tif" />

<img file="AU582178B2_D0031.tif" />

<img file="AU582178B2_D0032.tif" />

Example s 7 - 9

A ribbon of 1.3 mm float glass was coated with a barrier coating of silicon and oxygen as it advanced over the float bath by passing a mixture of monosilane, nitrogen and ethylene parallel to the glass surface under laminar flow conditions as described in U.K. Patent

Specification 1,507,996. The temperature of the glass at the coating station was 640°C and the lehr speed of the glass ribbon was 1200

<td> • &lt; &lt; Γ c</td><td> metres/hour.</td>

<td> t »· t t t tt t X. t</td><td> The gas flows and</td>

<td> r r t 11 &lt; € « C</td><td> obtained are set</td>

<td> Ct t r « t t t te e t « εc &lt;</td><td> The ion blocking</td>

<td> 15</td><td> the alkali metal</td>

properties of the products out in Table 3.

performance (as measured by ion extraction tests) , although not equal to the outstanding performance of earlier Examples, was comparable with commercially available glasses and satisfactory for commercially application.

The products had a high (about 90%) light

<img file="AU582178B2_D0033.tif" />

transmission ..

Example 10 - 13

Static samples of 4 mm float glass were coated in the laboratory by passing over the heated glass surface a coating gas comprising a mixture of nitrogen, 10% monosilane in

<img file="AU582178B2_D0034.tif" />

ι

<img file="AU582178B2_D0035.tif" />

• « · • · · • · · • · · β *» * :w; .··:.

&lt; · ·

<td> Example</td><td> Cone, of silane in nitrogen (% by volume)</td><td> Rate of flow of silane in nitrogen (litre/minute/metre width of glass)</td><td> Rate oi flow of ethylene (litre/minute/metre width of glass)</td><td> Molar ratio ethylene: silane</td><td> Light transmission* O' /0</td><td> Light Reflection* O' Λ</td><td> Alkali metal ion + extraction microgram/dm²</td>

<td> 7</td><td> 15</td><td> 40</td><td> 20</td><td> 3.3:1</td><td> 89.7</td><td> 8.8</td><td> 50</td>

<td> 8</td><td> 15</td><td> 30</td><td> 15</td><td> 3.3:1</td><td> 90.1</td><td> 8.7</td><td> 86</td>

<td> 9</td><td> 15</td><td> 30</td><td> 23</td><td> 5:1</td><td> 90.7</td><td> 8.2</td><td> 400</td>

Δ\„.

TABLE 4

<td rowspan="2"> Example</td><td rowspan="2"> EDC</td><td colspan="3"> Gas flow rate (litres/minute)</td><td rowspan="2"> EDC silane ratio</td><td rowspan="2"> Glass surface temperature (°C)</td><td rowspan="2"> Deposition time (seconds)</td><td rowspan="2"> Light transmission* V Λ</td><td rowspan="2"> Alkali metal ion+ extraction microgram/dm²</td>

<td> n₂</td><td> 10% SiH₄/N₂</td><td> EDC</td>

<td> 10</td><td> ethylene</td><td> 6.5</td><td> 0.11</td><td> 0.11</td><td> 10</td><td> 630</td><td> 60</td><td> 80</td><td> 18</td>

<td> 11</td><td> 1% xylene in nitrogen</td><td> 6.5</td><td> 0.11</td><td> 0.001</td><td> 0.1</td><td> 630</td><td> 90</td><td> 78</td><td> 22</td>

<td> 12</td><td> ammonia</td><td> 6.5</td><td> 0.11</td><td> 0.06</td><td> 5.5</td><td> 628</td><td> 70</td><td> 86</td><td> 18</td>

<td> 13</td><td> acetylene</td><td> 6.5 of 10% H₂ in N₂</td><td> 0.65</td><td> 0.65</td><td> 10</td><td> 625</td><td> 60</td><td> 88</td><td> 31</td>

* determined using a C.I.E. Illuminant C source on the side of the glass remote from the coating.

+ determined as described with reference to Examples 1 to 4.

Λ iKH'iromiw

i.

ni trogen c ompou nd gases us and a (EDC ) .

ed times and products

It will electron ethylene similar gaseous electron

The composition , glass temperatures properties e em of set out that the donating gives tra on barrier are transparent and denoting of and the coated

Table e of ompounds i proper other coating deposition glass gaseous n place of coatings with e s . The coatings and r ere c e t t r C t i

c oxygen derived from

Example s 14

Static in the compr i samples of laboratory the g1 a s mm float by pass ng mixture of 6 glass were coated coating gas litres/minute nitrogen , monosilane litres/minu of 10% by volume ethylene

3 0 °C times coati nitrogen and over the heated for times of from 10 litres/minute gl a s surface seconds .

The used and properties of gs are shown in Table the resulting

The observed light reflect!

on the coated glass increase produced after appearanc e to s with coatin time , the coating seconds bei ng s imilar in using only reflecting coatings produced small proportions of ethylene.

·. ' C , ' ' L-^;· ·' /W

I ·*

TABLE 5

<td> Example</td><td> Coating Time (seconds)</td><td> Light Transmission* &amp; Λ</td><td> Thickness nm</td>

<td> 14</td><td> 10</td><td> 89.0</td><td> 19</td>

<td> 15</td><td> 20</td><td> 85.2</td><td> 28</td>

<td> 16</td><td> 40</td><td> 79.2</td><td> 39</td>

<td> comparative</td><td> 80</td><td> 55.2</td><td> 74</td>

I ro

CD

I * determined using C.I.E. Illummant C source on the side oF the glass remote From the coating.

This s er coating i e s of iments shows that, as the me i and the coating thicknes the buil up , the oxygen available from gl a s due its the is us ed up and the ting deposited transparency .

This believed to be deposition of unoxidi silicon on top silicon initial transparent coati ng contai and oxygen derived from the glass

The coatings were all tested for durability

- f t c c • t f £ t against

IN Na 0 H visible external

Examples

Static coated alkali attack by imme r s i t 8 0 °C .

i gn of

In ea c attack sample s of 4 mm gas over compositi case, float the laboratory by the and properti there was minutes .

pas s were ng a ting hot glass surface

30 °C .

The coating gas used coating time the coated products are shown in

Table

In each case, the ratio gaseous electron donating compound:silane was adjusted to produc e a transparent coating

Example

A sample prepared t

by a technique similar that described in

E xample 1 to 4 at an ethylene to silane ratio of

5:1, and a sample of uncoated clear 6 mm float glass were coated /

** ·,

<img file="AU582178B2_D0036.tif" />

<td rowspan="3"> Example</td><td rowspan="3"> EDC</td><td rowspan="2"> Sas -Flows</td><td rowspan="2"> (litres7mi</td><td rowspan="2"> ----- ΜΤΓ inat«£) Γ</td><td rowspan="3"> rl I ·» w &gt;n Molar ratio * EDC:silane</td><td colspan="4"> •n n 0 ey ·~. “ ·- · ** Λ . Λ»» Λ rt -</td><td rowspan="3"> Alkali durability</td>

<td rowspan="2"> ·* ♦» *» λ « Cuatrng time (seconds)</td><td rowspan="2"> Light Transmission* O' Λ</td><td rowspan="2"> Thickness (nm)</td><td rowspan="2"> Alkali metal ion⁺Extraction microgram/'dm^</td>

<td> 10% SiH₄in N£</td><td> EDC</td><td> n₂</td>

<td> 17</td><td> carbon dioxide</td><td> 0.40</td><td> 0.40</td><td> 6.6</td><td> 10</td><td> 10</td><td> 88.4</td><td> -</td><td> -</td><td> poor</td>

<td> 18</td><td> carbon dioxide</td><td> 0.40</td><td> 0.12</td><td> 6.8</td><td> 3</td><td> 13</td><td> 85.0</td><td> 35</td><td> 40</td><td> poor</td>

<td> 19</td><td> dimethyl ether</td><td> 0.35</td><td> 0.56</td><td> 6.5</td><td> 16</td><td> 11</td><td> 88.9</td><td> 39</td><td> 26</td><td> good</td>

<td> 20</td><td> but-i-ene</td><td> 0.36</td><td> 0.24</td><td> 6.8</td><td> 6.7</td><td> 11</td><td> 89.4</td><td> 19</td><td> 18</td><td> -</td>

<td> 21</td><td> carbon monoxide</td><td> 0.34</td><td> 0.50</td><td> 6.6</td><td> 14.7</td><td> 12</td><td> 87.0</td><td> 25</td><td> 36</td><td> poor</td>

<td> 22</td><td> dimethylamine</td><td> 0.40</td><td> 0.30</td><td> 6.7</td><td> 7.5</td><td> 12</td><td> 89.4</td><td> 25</td><td> 84</td><td> -</td>

<td> 23</td><td> acetone</td><td> 0.38</td><td> 0.06</td><td> 6.8</td><td> 1.6</td><td> 12</td><td> 89.6</td><td> 14</td><td> -</td><td> -</td>

<td> 24</td><td> acetone</td><td> 0.11</td><td> 0.022</td><td> 7.0</td><td> 2</td><td> 90</td><td> 90.5</td><td> 20</td><td> 35</td><td> -</td>

<td> 25</td><td> ammonia</td><td> 0.35</td><td> 0.35</td><td> 6.7</td><td> 10</td><td> 12</td><td> 89.0</td><td> 22</td><td> -</td><td> good</td>

<td> 26</td><td> ammonia</td><td> 0.11</td><td> 0.06</td><td> 6.5</td><td> 5.5</td><td> 70</td><td> 86.0</td><td> -</td><td> 18</td><td> good</td>

<td> 27</td><td> isopropanol</td><td> 0.38</td><td> 0.013</td><td> 6.8</td><td> 0.3</td><td> 12</td><td> 79.5</td><td> 28</td><td> 40</td><td> good</td>

<td> 28</td><td> acetaldehyde</td><td> 0.38</td><td> 0.025</td><td> 6.9</td><td> 0.7</td><td> 12</td><td> 88.6</td><td> 21</td><td> 36</td><td> good</td>

<td> 29</td><td> water</td><td> 0.11</td><td> 0.004</td><td> 6.6</td><td> 0.4</td><td> 60</td><td> 86.0</td><td> 30</td><td> 181</td><td> poor</td>

<td> 30</td><td> nitric oxide</td><td> 0.40</td><td> 0.10</td><td> 6.9</td><td> 2.5</td><td> 11</td><td> 90.5</td><td> 40</td><td> 40</td><td> good</td>

<td> 31</td><td> nitrous oxide</td><td> 0.75</td><td> 0.15</td><td> 6.5</td><td> 2.0</td><td> 7</td><td> 89.0</td><td> 30</td><td> 13</td><td> poor</td>

<td> 32</td><td> ethylene oxide</td><td> 0.20</td><td> 0.08</td><td> 6.5</td><td> 4.0</td><td> 40</td><td> 91.0</td><td> 45</td><td> 13</td><td> -</td>

<td> 33</td><td> nitrogen dioxide</td><td> 0.40</td><td> 0.11</td><td> 6.9</td><td> 2.7</td><td> 12</td><td> 88.5</td><td> 40</td><td> 40</td><td> poor</td>

♦ determined using C.I.E. Illummant C source on the side of the glass remote from the coating. ⁺ determined as described with reference to Examples 1 to 4.

A &lt;&gt;

with fluorine doped tin oxide di fluoro tetrachlorostannate, was pin milled to a particle

Ammo ni um (NH4) 2 SnC14 F 2 r i z e not exceeding 50 microns, dispersed in air, and the air dispersed powder glass samples

0 grams per thickness of a stream of stream containing directed onto the the heated about 580°C at a rate of square metre of glass. The the resulting fluorine doped tin oxide coatings and their electrical resistivities were measured.

The results

<td> obtained are set rte</td><td> out below:</td><td></td>

<td> c e t ς r</td><td> Tin oxide</td><td> Specific</td>

<td> t r</td><td> thickness</td><td> Resistivity</td>

<td> :r. 15</td><td> ( nm)</td><td> (ohm cm)</td>

<td> Barrier coated substrate</td><td> 58</td><td> 1.7 x 10-3</td>

<td> Uncoated</td><td> 56</td><td> 3 x IO^-3</td>

substrate (

The significantly lower resistivity the coating on the barrier coated substrate illustrates the value of the barrier coating in inhibiting migration from the glass of l s’ alkali metal ions, with their deleterious effect on the resistivity of the doped tin oxide layer.

<img file="AU582178B2_D0037.tif" />

<img file="AU582178B2_D0038.tif" />

<img file="AU582178B2_D0039.tif" />

<img file="AU582178B2_D0040.tif" />

Example 35

Liquid crystal display devices as described herein were made up using g1ass carrying a transparent barrier coating produced substantially as described in Example 8 as a substrate, and subjected to durability testing. They were found to have lifetimes in excess of 1000 hours at 60°C and a relative humidity of 95%.

All the electron denoting^compounds used in the Examples were compounds having a Vapour f

r r &lt; i i ^r r t * t t ^r Γ l ♦ t ♦« «

X &lt; it I pressure above 760 mm at 60°C, except the following whose vapour pressure at 60°C is as s ta ted be low :

<td> Isopropanol</td><td> 40</td><td> kPa</td>

<td> Xy1e ne</td><td> 8</td><td> kPa</td>

<td> Water</td><td> 20</td><td> kPa</td>

<img file="AU582178B2_D0041.tif" />

<img file="AU582178B2_D0042.tif" />