CA2148954C

CA2148954C - Grey soda-lime glass

Info

Publication number: CA2148954C
Application number: CA002148954A
Authority: CA
Inventors: Camille Dupont; Daniel D'hont
Original assignee: Glaverbel Belgium SA
Current assignee: AGC Glass Europe SA
Priority date: 1994-05-11
Filing date: 1995-05-09
Publication date: 2002-10-08
Anticipated expiration: 2015-05-09
Also published as: KR950031955A; JP3127194B2; LU88486A1; NL1000336A1; GB9509098D0; KR100311319B1; JPH0859287A; ITTO950346A1; ITTO950346A0; IT1277995B1; SE9501727D0; AU690963B2; CZ120595A3; BR9501695A; CZ288338B6; BE1009686A3; ES2123373A1; DE19517121A1; FR2719838B1; US5728471A

Abstract

Grey soda-lime glass is composed of main glass-forming constituents together with iron, selenium, cobalt and chromium as colouring agents in the following quantities:
Fe2O3 0.5 to 0.9%
Co 0.012 to 0.025%
Se 0.0025 to 0.010%
Cr2O3 0.005 to 0.020%.
The proportions of colouring agents are such that the glass has a lighttransmission factor (TL) of less than 30% and an excitation purity (P) of less than 12%. The dark grey glass is especially appropriate for installation in the sunroofs of cars.

Description

~ 21~954 Grey soda-lime ~l~s~
The present invention concerns a grey coloured soda-lime glass comprising a base ..""~ i.". of main glass-forming c~nctihlr-nh together with colouring agents.
The expression "soda-lime glass" is used here in a broad sense and 5 denotes any glass that contains the following f~)nctitllr~nh ~p~ llL~ by weight):
SiO2 60 to 75%
Na2O 10 to 20%
CaO 0 to 16%
K2O 0 to 10%
MgO 0 to 10%
A12O3 0 to 5%
BaO 0 to 2%
BaO + CaO + MgO 10 to 20%
K2O + Na2O 10 to 20%
This type of glass is used very widely in the field of glazing for buildings or motor vehicles, for example. It is generally m~nllf~rhlred in the form of a ribbon by a drawing or float process. A ribbon of this type may be cut up in the form of sheets which may then be made curved or subjected to a treatment to 20 reinforce the ~ I,al~i~l properties, for example, heat tempering.
When discussing the optical properties of a sheet of glass, it is generally necessary to relate these properties to a standard illuminant. In the present.~l,~, ;ti, ,.li.,l~ 2 standard " lminAnh are used; Illuminant C and Illuminant A as defined by the IIIL~lllaLiullal t~.mmiCci-.rl on Tll~lmin~ti~rl (C.l.E.). Illuminant 25 C represents average daylight having a colour temperature of 6700 K This illuminant is especially useful for evaluating the optical properties of glazingpanels for buildings. Illuminant A represents the radiation of a Planck radiator at a t,r~mrDr~hlre of about 2856 K. This illuminant represents the light emitted by car hv~ and is essentially used to evaluate the optical properties of glazing 30 panels for motor vehicles. The 1,-~--,-,~1;..l,,,1 l'~rnmiccir~n on Ill-lrninAtir)n has also published a document entitled "Colorimehy, Official R~c~mmr~nrl~tk~ns of the C.l.E." (May 1970) which sets out a theory according to which the colcli.,l~LIi~ coordinates for the light of each w~v~ L~ of the visible spectrum , - - ~
21~g9~4 .
are defLned so that they may be ~ d on a diagram having orthogonal axes x and y called the C.l.E- L.i,l..u...aLk: diagram. This L~L~IIlulllauc diagram shows the locus for Gght of each wavelength (expressed in llal1ulll~Ll~) within the visible spectrum. This is known as the "spectrum locus" and the ILght whose 5 ~Ould;.laL~o are situated on thLs spectrum locus is said to possess a 100%
excitdtion purity for the aL L lu~JliaL~ wavelength. The spectrum locus is closed off by a line known as the purple line which joins the points of the spectrum locus,the ~ùuldillaL~s of which correspond to wavelengths of 380 nm (violet) and 780 nm (red). The area enclosed by the spectrum locus and the purple line is the ~0 field available for the Lli~ ulllaLic eu~l`dillaL~ of any vLsible light. The ~.uuldillaL~ of the light emitted by Illuminant C, for example, conrespond to x =
0.3101 and y = 0.3163. This point C is taken to represent white light and d.,wldill~lj has an excitation purity equal to zero for any wavelength. Lines may be drawn from the point C to the spectrum locus at any desired wavelength and 75 any point situated on these lines may be defined not only by its w~Jldillal~s x and y, but abo in terms of the wavelength corresponding to the line on which it is situated and its distdnce from the point C reldtive to the tOtdl length of the wavelength line. From this, light Llall~llliLL~d by a coloured sheet of glass may be described in terms of its dominant wavelength and its excitation purity expressed 20 in percent.
In fact the C.l.E. cuuldil~dLt::, of light ~ by a coloured glass sheet will depend not onLy on the ~UIII~JU~iLiUII of the glass but also on its thickness. throughout this .~I,e. ;ti.,~ including the claims, any value of the Lli~lllulllaLic ~uuldillaL~s (x,y~, of the excitation purity P, of the dominant 25 wavelength ~D of the Lldl.a..liLL~:I light, and of the light L~all~llli~iu~l factor of the glass (TL) are cakulated from the spec*lc Lnternal ~ (SIT) of a 5 mm thick glass sheet. The specific internal ~ . "i~ . of a glass sheet is governed solely by the absorption of the gldss and can be expressed accordLng to the Beer-Lambert law; SIT = e~E A where A is the absorption coefficient of the c~lass (in30 cm~l) and E is the thickness of the glass (in cm). As a first a~ lu~illlaLiul~, SIT
may also be l~l~. llL~ by the formula (13 + R2) / (11 - R1) where 11 Ls the intensity of the incident visible light on the fLrst face of the glass sheet~ R1 Ls the intensity of the visible light reflected by thLs face, 13 is the intensity 35 of the visible light l.~m~ v~l from the second face of the glass sheet and R2 is the intensity of the visible light reflected internally by this second face.
In the following .~.I.æ. ;t;, ~ , including the claims, the following are used:

2~9~4 .
- the total light Llallallliaaiull for illuminant A, measured for a thickness of 4 mm (TLA4). This total Lla~lblllia~k)ll is the result of integrating the expression:~ T~,E~,.S~:.E~,.S~
between the wavelengths 380 and 780 nm, in which T~, is the Llallalllia~k~ll at 5 wavelength ~, E~, is the spectral rlictrihlltif)n of illuminant A and S~, is the sensitivity of the normal human eye as a function of the wavelength ~.
- the total energy L-~ ";~ -, measured for a thickness of 4 mm (TE4). This total ~ " ,;~ is the result of integrating the expression:
~:T~,.E~:.E~, 70 between the wavelengths 300 and 2150 nm, in which E~,, is the spectral energy distribution of the sun at 30 above the horLzon.
- the total Llallall~iaai~ll in the ultraviolet, measured for a thickness of 4 mm (TUVT4). This total Lla~lallliaaioll iâ the result of integrating the ~ caaiu~.
~:T~,.U~:.U~, 75 between the wavelengths 280 and 380 nm, in which U~, is the spectral distribution of ultraviolet radiation having passed through the atrnosphere, as determined as in DIN standard 67507.
The present invention concerns in particular dark grey glasses with a bluish shade. When the Ll,.~ curve of a L~ a~a~ L substance varies 20 hardly at all as a function of the visible wavelength, this substance is described as "neutral grey". In the C.l.E. system, it does not possess a dominant wave~ength and its excitation purity is zero. By extension, a body may be considered as grey for which the spectral curve is relatively flat in the visible region but nevertheless exhibits weak absorption bands, enabling a dominant wavelength to be defined 25 and a purity that is low but not zero. The excitation purity of grey glass ina~.,.da~ with the present invention Ls Less than 12%, preferably less than 5%.
Grey glass according to the present invenffon preferably has a dominant wavelength between 460 and 500 nm, corresponding to a bluish shade. The glass has a dark grey tint ~ a~ lldillg to a light Ll,.. l~ factor of less than 30 30%.
Grey gbsses are generally selected for their protecting properties against solar radiation and their use in buildings is known, especially in very sunny countries. Grey glasses are also used in balcony h~lllctr~oc or staircasesas well as for partial glazing in certain motor vehicles or railway c~,..l~,a-L--~t:.lb to 35 shield their contents from view. In order to illustrate these known glasses, French patent 2,0æ,459 in the name of Compagnie de Saint-Gobain may be quoted.
According to this patent, it is l~ orl that a glass be made having a total solar energy ~ lesc than 50% in which the luminance factor Y lies 21~g9~4 between 35 and 55% for a glass thickness from 2 to 12 mm (the luminance factor Y corresponds to the TL factor used in the present ~I..~. ,ri.,.li~,.,) In particular, for grey glass, the luminance factor Y lies between 35 and 45% in order to ensure a ~UIII~IUIIIis~ between efficient solar protection and sufficient luminosity in dull weather. Such a glass is suitable for architectural purposes in temperate regions but is insufficient when there is a need for more absorbent glasses, for instance when the interior of a car having a sunroof needs to be protected against solar radiation or dazzle from hf~ mrs at night.
The present invention concerns a dark grey glass especially 70 a~ uuliaL~ for installation in the sunroofs of cars.
The present invention provides a grey soda-lirne glass composed of main glass forming constituents together with colouring agents, characterised inthat iron, selenium, cobalt and chromium are present in the glass as colouring agents, in amounts cu..~a~u".li,lg to the following percentage p~upul~iul~s by 15 weight of the glass:
Fe2O3 0 5 to 0.9%
Co 0.012 to 0.025%
Se 0.0025 to 0.01û%
Cr2O3 0.005 to 0.020%
the proportions of colouring agents being such that the glass has the following light transmitting properties:
- light L~alDllliaaiUI~ factor (TL) less than 30%
- excitation purity (P) less than 12%.
We were surprised to observe that a dark grey glass of this type could be obtained with colouring agents the nature and ~ull~ aLiull of which are similar to those claimed by French patent 2,082,459. In point of fact the latter teaches that in a soda-lime glass, the presence of iron, cobalt, selenium and chromium colouring agents in the following ,u~ulJulLiulls:
Fe2O3 0.2 to 1%
CoO 0.003 to 0.03%
Se 0 to 0.010%
Cr2O3 0.003 to 0.020%
leads to a grey glass, the luminânce factor of which lies between 35 and 45%
(more than 40% according to the examples) and hence a llall~llliaaiUIl factor TLclearly above 30%.
In fact, glass having broadly similar colour properties can be produced by using nickel as the main colouring agent. The presence of nickel however presents certain disadvantages, especially when the glass has to be =

-~1~89~

produced by the float process. In the float process, a ribbon of hot glass is led along the surface of a bath of molten tin so that its faces become plane and parallel. In order to prevent oxidahon of the tin at the surface of the bath, which would lead to t:llL.<lilll~l~llL of tin oxide by the ribbon, a reducing ahmosphere is maintained above the bath. When the glass contains nickel7 this is partially reduced by the atmosphere above the hn bath giving rise to a haze in the glass produced. In addition, nickel present in the glass may form nickel sulphide NiS.This sulphide has various crystaLine forms, which are stable within different t~rnr~hlre ranges. Tl~ ;.", from one of these fomms to another creates problems when the glass has to be reinforced by a heat tempering hreatment, as is the case in the automotive field and also for certain glazing panels used in buildings (balconies, spandrels, etc.). GLass according to the invention, which does not contain nickel, is thus pArt~ rly weL adapted to be fommed by the floatprocess and also for architechural use or in the field of motor or other vehicles.
The combined presence of iron, cobalt, selenium and chromium colouring agents enables the optical and energy properties of grey glass according to the invenhon to be conhrolled. The effects of various colouring agents considered individually for the preparahon of a glass are as follows (according to "Glass" by H.Scholtze - translated by J.Le Dû - Glass Institute -Paris):
- Iron: Iron is in fact present in almost aL ~:vl~ Ly produced glasses, either as an impurity, or inkoduced deliberately as a colouring agent. The presence of Fe3+ ions, gives rise to a slight absorphon of visible Lght having a short wavelength (410 and 440 nm) and a very strong absorption band in the ultraviolet (absorption band centred on 380 nm), whereas the presence of Fe2+
ions gives rise to a strong absorption in the infrared (absorption band centred on 1050 nm). Ferric ions impart to the glass a mild yeLow colour whereas ferrous ions give a stronger blue-green coloration.
- Selenium: The Se4+ cahon has practicaLy no colouring effect, whereas the uncharged element Se imparts a pink coloration. The Se2- anion forms a ull~v~hvl~c with ferric ions present and on account of this gives a brownish redcolour to the glass.
- Cobalt: The ~roup colIO4 produces an intense blue coloration with a dominant wavelength almost opposite to that imparted by the iron-selenium ~ vlllv~hvl~.
- Chromium: The presence of the group Crl1lo6 gives rise to absorption bands at 650 nm and gives a Lght green colour. Strong oxidation gives rise to the group CrV104 which gives a very intense absorption band at 365 nm and gives a yellow colorahon.

21~9~

.
The ener~y and optical propertLes of glass containing these different colouring agents thus results from a complex interaction between them,each of these colouring agents having a behaviour which depends strongly on its redox state and thus, on the presence of other elements likely to influence thisstate.
We have noted that when the ~lupulLiulls of cobalt, selenium and chromium colouring agents lie between the limits defined above, they enable the lowest possible total light Ll~ to be attained, evaluated for illuminant A
(TLA4) taking into account the maximum content of 0.9% iron (evaluated in the form of Fe2O3). Glass according to the invention preferably possesses a total light llall~lllia~lull TLA4 of between 1û and 357O which makes it particularly useful for overcoming dazzle by light frûm vehicle hPAfllArnrs when it Ls used for side and rear windows or in the roof of motor vehicles. When the proportion of cobalt falls below the limits defined above, for example to 100 ppm, and the proportion of chromium falls below the limits defined above, for example to 35 ppm, we have found that the light Llanallli~iull factor (TL~ increases, for example to 33% or more.
The presence of iron and selenium colouring agents within the limits defined above allows a strong absorption in the ultra violet region. Glass according to the invention preferably possesses a total Lal~llli~aiul~ in the ultraviolet region (TWT4) of less than 14%. This property is particularly advantageous in the automotive field. The lower ~ of ultraviolet radiation avoids or reduces the ageing and ~ r~tinn of interior trim in motor vehicles.
The low chromium content of glass in accordance with the invention favourably limits the oxidation rhvnnmRnnn of iron in the glass. This low content allows one to keep a maximum of iron in the bivalent fomm, which imparts the glass a high absorption of infrared radiation. The total energy Llal~lll;~Diull of the glass (TE4) Ls preferably between 20 and 40%.
The bluish shade of the glass is essentially associated with the cullllJillaLiu~ of cobalt and selenium agents.
In a particularly prefenred v~ u~ l of the invention, the grey glass Ls llala~L~ L by the presence of colouring agents in amounts corresponding to the following percentage plulJulLiulls by weight of glass:
Fe23 0.57 to 0.70%
Co 0.017 to 0.020%
Se 0.005 to 0.008%

2~4~4 .
Cr2O3 0.016 to 0.020%
the ~lUlJUlLiUI-s of the colouring agents being such that the glass has the following light Lla~allliLLillg properties:
- light L~ allliaaiull factor (TL) between 16 and 22%
5 - excitation purity (P) less than 6%.
Within these preferred limits, it is possible to obtain a glass of which the total Gght Llallallliaa;ull for illuminant A (TIA4) lies between 20 and 25%, and the total energy Ll~allliaaiull (TE4) Lies between 30 and 35%.
Glass correspondLng to the more restricted ~ull~t ~lLIaLiul~ range of 10 colouring agents defined above is particularly effective since it combines the properties of low energy Llallallliaaiu~ and low light Ll.lnallliaaiul~ which makes it perfectly adequate for being used as sunroofs in motor vehicles or for use in buildings situated in very sunny counhries. In its architechural use, its aesthetic properties combine with high energy savings linked with the least demands on airrs ~u~diLiu~ g systems.
Such a glass is preferably used in sheet form, for example at a thickness of 4 or 5 mm for the m~nll~hlre of sunroofs, 3 mm for side and rear windows in motor vehicles and more than 4 mm in buildings.
The glasses according to the present invention can be made by 20 conventional methods. As raw materials, either natural materiaLs, recycled glass, slag or some .: .""l ,;",.l;. ", thereof may be used. The colorants are not necessarily added in the form shown but it is conventional to give the quantities of added colouring agents, in equivalents in the forms shown. In practice, iron may be added as rouge, cobalt as a hydrated sulphate such as CoSO4.7H2O or 25 CoSO4.6H20, selenium may be added in the elementary form or as a selenite such as Na2SeO3 or ZnSeO3, and chromium may be added as a bi~l,lulll~L~:
such as K2Cr2O7. Other elements are sometimes present as impurities in the starting materials used for forming the glasses according to the invention, (such as, for example, I ~ e oxide at a level of the order of 50 ppm) either in the 30 natural materials or in re-cycled glass or slag, but where the presence of such impurities does not take the properties of the glass outside the limits deflned above, such glasses are ~ullaid~ l to be within the scope of the present invention.
In another advanhgeous ~:lllbudilll~llL of the invention, the grey 35 glass is associated with a coating of at least one metal oxide, for example a coating composed of tihnium oxide, tin oxide, iron oxide, cobalt oxide, chromium oxide or a mixture of these.

~ 1~8~

A glass bearing such a coating preferably has, for a thickness of 4 mm, a light llal~ iull factor (illuminant C) less than 15%, an energy factor less than 25%, and a total l~,.o~ for ultraviolet less than 5%.
Such a glass has optical and energy properties which âre difficult to obtain solely with a bulk coloured glass; these low Ll~ aiull~ can normally only be attained with very Large quantities of iron which make the vitrifiable batch difficult to melt.
The present invention will be illustrated by the following specific examples of ~ u~ili". ,.s according to the invention.
FY~n~ploc 1 tn ~3 Table I yives the base c~ of the glass as weL as the ~nnctih~ontc of the vitrifiable batch to be melted in order to produce glasses according to the invenhon (the quantities being expressed in hiluyl~ per tonne of vitrifiable batch). Table ll gives the colorants to be added to the batch (the quantities being expressed in ~ I ,~,,,.,,.,, ~ for 1 tonne of vitrifiable raw materials). Tables Illa and Illb give the plul.ulLio~ls by weight of colouring agents in the glass produced. These ~ulJu~Liuns are determined by X-ray fluorescence of the glass and converted into the molecular species shown. Tables Illa and Illb also give the optical and energy properties corresponding to the definitions given in the present ~I,PI ;~i. ,.lil~, . In these tables, "TL x mm" has the same definition as "TL" but with the thi~knoccPs indicated and not with 5 mm.
Example 7 relates to a glzss according to Example 5 on which a layer of iron, cobalt and chromium oxides has been deposited. Such a layer has a thickness of between 35 and 45 nm. It contains, in p,~,~.o.Liol-s by weight, 62%
of cobalt oxide, 26% of iron oxide and 12% of chromium oxide. Such a layer is easily obtained by pyrolysis of or~nnmot-" reagents such as ~ro~tyl~otnnate on the glass ribbon whiLst it is still hot, at the exit from the float tank.
Example 8 relates to a glass according to Example 5 on which a layer of titanium oxide has been deposited to a thickness of between 45 and 50 nm. This layer is deposited by pyrolysis of an organic titanium compound on the hot glass.

~1~8g~
.
T~RI F l; I~ F G~
Analysis of h~co Qlass SiO2 72.0%
A12O3 0.8%
CaO 8.8%
MgO 4.2%
Na2O 14.1%
K2O 0.1%
Conc ih lontC of bAco ~ cc Sand 571.3 Feldspar 29.6 Limestone 35.7 Dolomite 162.1 Na2C3 181.1 r5 Sulphate 10.1 Nihrate 10.1 T~RL~ 11 Colouring agents (kg) calculated in the form of:
F~x~mnl~ No: 1 2 3 4 5 6 Fe2O3 4.77 4.94 5.19 4.66 4.85 4.81 CoO 0.18 0.18 0.19 0.18 0.1g 0.19 Se 0.07 0.07 0.11 0.12 0.17 0.15 K2Cr2O7 0.29 0.28 0.27 0.31 0.29 0.31 Colouring agents (quantity by weight in the glass~ calculated in the form of:
Fe2O3 (%) 0.581 0.602 0.632 0.567 0.59 0.585 Co (ppml 175 174 182 170 184 182 Se (ppm) 34 32 54 59 86 76 Cr2O3 (ppm) 181 174 170 194 183 193 1214~9~
.
T~!RI F
Properties of the glass:
Fv~mr)l~ No: 1 2 3 4 TL(%) 24.1 24.4 20.9 21.7 P (%) 11.6 10.8 5.6 4.9 ~D (nm) 480.6 481.1 481.6 481.0 TLA4 (%) 28.6 28.7 25.7 26.3 TE4 (%) 35.9 35.1 ~ 32.8 33.9 TUVT4 (%) 11.8 10.6 7.3 10.9 TL 4 mm 31.7 32.0 28.3 29.0 TL 6 mm 18.6 18.9 15.7 16.3 TL12 mm 3.8 3.9 2.7 2.9 T~RT F Illb Properties of the glass:
FY~n~ No: 5 6 7 8 TL(%) 19.8 17.8 7.8 13.3 P (%) 0.13 0.8 12.4 5.5 ~D (nm) 494.7 478.2 580.4 578.9 TLA4 (%) 25.0 22.9 - -TE4 (%) 36.9 33.0 24.0 31.5 TUVT4 (%) 6.0 6.2 1.9 3.9 TL4 mm 27.6 24.9 10.7 18.4 TL 6 mm 15.1 13.0 5.7 9.7 TL 12 mm 2.5 1.8 O.g 1.5 FY~n~l~c 9 ~nr~ 10 Followin~ the procedure described in connection with Examples 1 to 8 above,the following ~lasses were formed and tested for their properties, which were as set out in the following T~RLE IV. Example 10 relates to a glass 5 in accordance with Example g on which a layer of iron, cobalt and chromium oxides has been deposited as described in connection with Example 7 above.

~1489~

-TABLE IV
Constituer-tc of base glass Sand 587 Dolomite 201 Na2C3 172 Al(OH)3 20 Sulphate 10 Mtrate 10 Colouring a~enk Fe2O3 5.50 CoO 0.20 Se 0.11 K2Cr2O7 0.30 Colouring agents:
Example No: 9 10 Fe2O3 (%) 0.655 0.655 Co (ppm) 187 187 Se (ppm) 58 58 Cr2O3 (ppm) 190 190 Properties of the glass:
Fx~n~pl~ N: 9 10 TL(%) 17.2 6.3 P (%) 3.2 9.1 ~D (nm) 479.0 579.7 TLA4 ( %) 22.3 TE4 (%) 30.g 17.9 TWT4 (%) 7.1 1.5 TL 4 mm - 8.9

Claims

1. Grey soda-lime glass having a dark grey color, comprising soda-lime glass and coloring agents comprised of iron, cobalt, selenium and chromium in amounts, based on the weight of the glass, of:
from 0.5 to 0.9% of Fe2 O3;
from 0.012 to 0.025 of Co;
from 0.0025 to 0.010% of Se; and from 0.005 to 0.020% of Cr2O3, wherein the glass has light transmitting properties including a light transmission factor (TL) of less than 30% for a glass thickness of 5 mm, and an excitation purity (P) of less than 12%.

2. The grey soda-lime glass according to claim 1, wherein the glass has a total light transmission, measured for a glass thickness of 4 mm with illuminant A (TLA4), which ranges from 10 to 35%.

3. The grey soda-lime glass according to claim 1, wherein the glass has a total energy transmission, measured for a glass thickness of 4 mm (TE4), which ranges from 20 to 40%.

4. The grey soda-lime glass according to claim 1, wherein the glass has a dominant wavelength which lies between 460 and 500 nm.

5. The grey soda-lime glass according to claim 1, wherein the glass has an total ultraviolet transmission, measured for a glass thickness of 4 mm (TUVT4), which is less than 14%.

6. The grey soda-lime glass according to claim 1, wherein the glass is a sheet of glass.

7. The grey soda-lime glass according to claim 6, further comprising a coating layer consisting of at least one metal oxide provided on at least one surface of the sheet of glass to provide a coated glass sheet.

8. The grey soda-lime glass according to claim 7, wherein the coated glass sheet has, for a coated glass sheet thickness of 4 mm, a light transmission factor of less than 15% (illuminant C), an energy transmission factor of less than 25% and a total ultraviolet transmission of less than 5%.

9. The grey soda-lime glass according to claim 8, wherein the sheet of glass is placed in a sunroof of a motor vehicle.

10. The grey soda-lime glass according to claim 6, wherein the sheet of glass is placed in a sunroof of a motor vehicle.

11. The grey soda-lime glass according to claim 1, wherein the soda-lime glass is comprised of:
from 60 to 75 weight percent of SiO2;
from 10 to 20 weight percent of Na2;
from 0 to 16 weight percent of CaO;
from 0 to 10 weight percent of K2O;
from 0 to 10 weight percent of MgO;
from 0 to 5 weight percent of Al2O3;
from 0 to 2 weight percent of BaO;
from 10 to 20 weight percent of a mixture consisting essentially of BaO, CaO, and MgO; and from 10 to 12 weight percent of a mixture consisting essentially of K2O
and Na2O.

12. The grey soda-lime glass according to claim 11, wherein the grey soda-lime glass has a thickness ranging from 2 to 12 mm.

13. The grey soda-lime glass according to claim 12, wherein the grey soda-lime glass has a thickness ranging from 3 to 5 mm.

14 Grey soda-lime glass having a dark grey color, comprising soda-lime glass and coloring agents comprised of iron, cobalt, selenium and chromium in amounts, based on the weight of the glass, of:
from 0.57 to 0.70%% of Fe2O3;
from 0.017 to 0.020% of Co;
from 0.005 to 0.008% of Se; and from 0.016 to 0.020% of Cr2O3, wherein the glass has light transmitting properties including a light transmission factor (TL) which ranges between 16 and 22% for a glass thickness of 5 mm, and an excitation purity (P) of less than 6%.

15. The grey soda-lime glass according to claim 14, wherein the glass has a total light transmission, measured for a glass thickness of 4 mm with illuminant A (TLA4), which ranges between 20 and 25%.

16. The grey soda-lime glass according to claim 14, wherein the glass has a total energy transmission, measured for a thickness of 4 mm (TE4), which ranges between 30 and 35%.

17. The grey soda-lime glass according to claim 14, wherein the glass is a sheet of glass.

18. The grey soda-lime glass according to claim 17, further comprising a coating layer consisting of at least one metal oxide provided on at least one surface of the sheet of glass to provide a coated glass sheet.

19. The grey soda-lime glass according to claim 18, wherein the coated glass sheet has, for a coated glass sheet thickness of 4 mm, a light transmission factor of less than 15% (illuminant C), an energy transmission factor of less than 25%, and a total ultraviolet transmission of less than 5%.

20. The grey soda-lime glass according to claim 19, wherein the sheet of glass is placed in a sunroof of a motor vehicle.

21. The grey soda-lime glass according to claim 17, wherein the sheet of glass is placed in a sunroof of a motor vehicle.

22. The grey soda-lime glass according to claim 14, wherein the soda-lime glass is comprised of:
from 60 to 75 weight percent of SiO2;
from 10 to 20 weight percent of Na2O;
from 0 to 16 weight percent of CaO;
from 0 to 10 weight percent of K2O;
from 0 to 10 weight percent of MgO;
from 0 to 5 weight percent of Al2O3;
from 0 to 2 weight percent of BaO;
from 10 to 20 weight percent of a mixture consisting essentially of BaO, CaO, and MgO; and from 10 to 12 weight percent of a mixture consisting essentially of K2O
and Na2O.

23. The grey soda-lime glass according to claim 22, wherein the grey soda-lime glass has a thickness ranging from 2 to 12 mm.

24. The grey soda-lime glass according to claim 23, wherein the grey soda-lime glass has a thickness ranging from 3 to 5 mm.