FR3002533A1 - SUBSTRATE FOR ORGANIC ELECTROLUMINESCENT DIODE DEVICE - Google Patents

Abstract

The subject of the invention is a diffusing substrate for an organic light-emitting diode device comprising a glass sheet coated on one of its faces with a layer comprising a vitreous material, such that said vitreous material has a chemical composition comprising the following constituents, varying within the weight limits defined below: Bi203 60-85% B203 5-12% SiO2 6-20% MgO + ZnO 0-9.5% Al2O3 0-5% Li2O + Na2O + K2O 0-5% CaO 0- 5% BaO 0-20%.

Description

The invention relates to the field of substrates for organic light-emitting diode devices. It relates more specifically to chemical compositions of vitreous material and glass frits particularly well suited to the formation of layers.

Organic light-emitting diode devices, which will be referred to hereinafter by their acronym OLED, usually used in the art, are devices emitting light by virtue of an electroluminescence phenomenon. These OLED devices generally include an organic electroluminescent system between two electrodes. One of the electrodes is deposited on a glass sheet in the form of an electroconductive layer. OLED devices can be used as display screens or as lighting devices. In an application as a lighting device (lamp, etc.), the light extracted from the device is a white, polychromatic light. The light extraction efficiency is, however, naturally low, of the order of 0.25, the light being trapped inside the device because of differences in refractive indices between its different elements. To solve this problem, it is known, for example from the application WO 2011/089343, to arrange between the glass sheet (of index 1.5 when it is made of silica-calcium glass) and the electrode, a layer internal diffusing material comprising a vitreous material of high refractive index (typically between 1.7 and 2.0) and diffusing elements, for example particles. The aforementioned application describes vitreous materials whose chemical composition comprises 40 to 60% by weight of Bi 2 O 3 and 5 to 30% by weight of ZnO. The vitreous materials are generally obtained by a process in which a glass frit (with the same chemical composition as the material) is mixed with a typically organic medium to form a paste, which is deposited on the glass sheet before it is baked. . The glass transition temperature of the glass frit must be low enough to be able to cook at temperatures at which the glass sheet can not be deformed. At the same time, the frit must not crystallize (devitrify) during cooking, which would have the effect of generating too much roughness and high optical absorption. The linear thermal expansion coefficient of the frit must also be adapted to that of the glass sheet, generally be close to the latter, or slightly lower, in order to avoid during the cooling the appearance in the glassy material of mechanical stresses susceptible to damage it. In order to prevent the deposit of dust on the layer likely to create a short circuit, it is customary to carry out a thorough cleaning of the layer before the deposition of the electroconductive layer. This cleaning usually involves passages in ultrasonic tanks where the layer is subjected to the action of detergents, successively basic (to take off the particles remained on the surface) and acids (to neutralize the surface of the layer and avoid any redeposition of particles). The acid attack is likely to degrade the vitreous material, creating an unacceptable surface roughness for the final application. The object of the invention is to provide compositions of vitreous material (and glass frit) having a good compromise between an improved chemical resistance, in particular to acids, a high refractive index, a coefficient of thermal expansion and a transition temperature. vitreous, and low ability to devitrification.

To this end, the subject of the invention is a diffusing substrate for an organic light-emitting diode device comprising a glass sheet coated on one of its faces with a layer comprising a vitreous material, such that said vitreous material has a chemical composition comprising the following constituents, varying within the following weight limits: Bi203 B2O3 SiO2 Mg0 + ZnO A1203 Li2O + Na2O + K2O Ca0 BaO 60-85% 5-12% 6-20% 0-9.5% 0-5% 0 -5% 0-5% 0-20%.

The invention also relates to an organic light-emitting diode device comprising a diffusing substrate according to the invention, wherein an electroconductive layer is disposed on the layer comprising a vitreous material.

By the use of "over" or "under" terms, one does not necessarily mean that the layers are in contact, only that they are closer to the substrate ("under") or more distant ("on"). The case where the layers are in contact is however not excluded. The subject of the invention is also a glass frit whose chemical composition comprises the following constituents, varying within the weight limits defined below: Bi 2 O 3 B2O 3 SiO 2 MgO + ZnO Al 2 O 3 Li 2 O + Na 2 O + K 2 O Ca 2 BaO 60-85% 5 -12% 6-20% 0-9.5% 0-5% 0-5% 0-5% 0-20%. The preferred characteristics in terms of oxide contents which are detailed below also relate to the chemical composition of the vitreous material deposited on the glass sheet as well as that of the glass frit (used for the deposition). Throughout the text, the contents indicated are weight contents. The weight content of Bi 2 O 3 is advantageously at least 62%, in particular 63% and even 64% or 65% and / or at most 83%, especially 82% or even 81%, even 80%, 79% or 78%. It is preferably in a range from 65 to 80%, especially 68 to 75%. Too low a content of Bi 2 O 3 does not provide the desired refractive indices, while too high a content leads to unacceptable glass yellowing.

The weight content of B203 is preferably at least 6%, especially 7% or 7.5% and / or at most 11%, especially 10%, or even 9.5% or 9%. It is preferably in a range from 6 to 11%, especially from 7 to 10%. A high content of B203 has the effect of increasing the glass transition temperature and lowering the chemical resistance of the material, while a too low content makes the glass more easily devitrifiable. The weight content of SiO 2 is preferably at least 7%, in particular 7.5% or even 8% and / or at most 18%, 17%, 16%, 15%, 14%, or 13%, especially 12% or 11% and even 10% or 9%. It is preferably in a range from 7 to 12%, especially 7.5 to 10%. Too high a SiO 2 content causes a detrimental reduction in the refractive index, while a too low content decreases both the chemical resistance and the thermal stability. The weight content of ZnO is preferably at most 9.5%, especially 9% or 8%, even 7% or 6% or 5%, and even less than 5%. According to one embodiment, the ZnO content is even at most 1%, especially 0.5%, or 0.1%, or even zero. The weight content of ZnO is preferably in a range from 2 to 8%, especially from 3 to 6%. High levels of ZnO counteract good chemical resistance, especially to acids, and increase the risk of devitrification. The weight content of MgO is preferably at most 3%, especially 2.5% and even 2%. In some embodiments, this content is even less than 0.5% and even 0.1%, or even zero. In another embodiment, the MgO content is at least 0.5%, especially 1%, more particularly in a range from 0.5 to 3%, especially from 1 to 2.5%. The addition of Mg0 makes it possible to improve the chemical resistance of the vitreous material.

The sum of the weight contents of MgO and ZnO (MgO + ZnO) is advantageously at least 1%, in particular 2% or 3% and even 4 or 5% and / or at most 9%, in particular 8% and even 7%. It is preferably in a range from 2 to 9%, especially from 3 to 8% or from 2 to 5%. It appeared that a cumulative content of MgO and ZnO too high resulted in a risk of devitrification during the manufacture of the frit. The weight content of CaO is preferably at most 4% and even 3% or 2%. In some embodiments, this content is even less than 0.5% and even 0.1%, or even zero. In another embodiment, the CaO content is at least 0.5%, especially 1%, more particularly in a range from 1 to 4%, especially 1.5 to 3.5%. The sum of the weight contents of CaO and MgO is preferably at least 0.5%, especially 1% or 1.5%, or even 2% or 3%. According to one embodiment, it may, however, be less than 0.5% and even 0.1%, or even zero. The sum of the weight contents of CaO and MgO is preferably in a range from 0.5 to 4%. The addition of CaO and / or MgO, in addition to a decrease in the ZnO content improves the acid resistance of the vitreous material. The A1203 content is preferably at least 1%, especially 2%. It is preferably in a range from 1 to 4%, especially 2 to 3%. The addition of alumina improves the chemical resistance of the material. The BaO content is advantageously at most 10%, especially 5% and even 3% or even 1% or 0.5%, or even 0.1%. It can even be zero.

The total content of alkaline oxides (Li 2 O, Na 2 O, K 2 O) is preferably at most 3%, especially 2% and even 1% or 0.5%. According to a preferred embodiment, this content is preferably in a range from 0.02 to 1%, especially from 0.05 to 0.2%. In this case, the only alkaline oxide present is advantageously Na 2 O. The addition of alkaline oxides, even at low levels, has the effect of significantly reducing the glass transition temperature. For each of the oxides or groups of oxides mentioned above, each of the lower bounds can be combined with each of the upper bounds, the set of possible ranges not being recalled here for the sake of brevity. Similarly, each range for a given oxide can be combined with any other range for the other oxides. Here again, not all combinations can be indicated so as not to unnecessarily burden the present text. Some preferred combinations are recalled in Tables 1 and 2 below. 1 2 3 4 5 Bi203 60-85 65-80 70-78 65-80 65-80 B203 5-12 6-11 7-10 6-11 6-11 Si02 6-20 7-12 7.5-10 7 -12 7-12 Mg0 + ZnO 0-9.5 2-9 3-8 2-5 2-9 A1203 0-5 1-4 2-3 1-4 1-4 Li20 + Na2O + K20 0-5 0 -2 0.05-0.2 0-2 0-2 Ca0 0-5 0-3 0-2 0-3 1-4 Ba0 0-20 0-5 0-1 0-5 0-5 Table 1 6 7 8 9 10 Bi203 60-85 65-80 70-78 65-80 65-80 B203 5-12 6-11 7-10 6-11 6-11 Si02 6-20 7-12 7.5-10 7- 12 7-12 ZnO 0-9.5 2-8 3-6 2-8 0-1 Mg0 0-3 0.5-3 1-2.5 0-2 1-2.5 Mg0 + ZnO 0-9 3-9 2-9 A1203 0-5 1-4 2-3 1-4 1-4 Li20 + Na2O + K20 0-5 0-2 0.05-0.2 0-2 0-2 Ca0 0 -5 0-3 0-2 1-4 0-5 Ba0 0-20 0-5 0-1 0-5 0-5 Table 2 Tables 1 and 2 define 10 particularly preferred compositions resulting from combinations of ranges defined above. . It goes without saying that each of these ranges can be combined with any other range from the tables for the other oxides. Preferably, the sum of the weight contents of Bi 2 O 3, B 2 O 3, SiO 2, ZnO, MgO, BaO and CaO is at least 95%, especially 96% or 97% and even 98% or 99%. Preferably, the sum of the weight contents of Bi 2 O 3, B 2 O 3, SiO 2, ZnO, MgO and CaO is at least 95%, especially 96% or 97% and even 98% or 99%. The total content of P205, Nb205 and V205 is preferably at most 1%, especially 0.5%, and even zero. The composition is preferably free of lead oxide. The total content of TiO2 and ZrO2 is preferably at most 1%, especially 0.5% and even 0.1%, or even zero, these oxides having a detrimental effect on the devitrification of this type of glasses. The total content of coloring elements (Fe 2 O 3, CuO, CoO, Cr 2 O 3, MnO 2, Se, Ag, Cu, Au, Nd 2 O 3, Er 2 O 3) is also preferably zero (except for unavoidable impurities).

The refractive index for a wavelength of 550 nm of the glass constituting the vitreous material or the glass frit is preferably in a range from 1.8 to 2.2, in particular from 1.85 to 2, 1, and even 1.88 to 2.0, or even 1.89 to 1.98.

The glass transition temperature Tg of the glass constituting the vitreous material or the glass frit is preferably in a range from 440 to 500 ° C., in particular from 450 to 480 ° C. The glass transition temperature is measured by Differential Scanning Calorimetry (DSC), under nitrogen, with a temperature rise rate of 10 ° C / min. We consider here the beginning of the curve ("onset temperature") for the determination of the Tg.

The difference between the crystallization temperature Tx and the glass transition temperature Tg is preferably at least 100 ° C in order to avoid any devitrification of the vitreous material during its shaping. The crystallization temperature is determined by taking into consideration the onset of crystallization (onset temperature), obtained by differential scanning calorimetry. The coefficient of linear thermal expansion between 20 and 300 ° C. of the glass constituting the vitreous material or the glass frit is preferably in a range from 70 to 100 × 10 -7 / ° C., in particular 75 to 95 × 10 -7 / ° C. , and even 80 to 90.10-7 / ° C.

The glass sheet preferably has a refractive index for a wavelength of 550 nm in a range from 1.4 to 1.6. It is preferably a glass of the silico-soda-lime type, obtained by the float process (known as the "float" process), of pouring the molten glass on a bath of molten tin. The glass sheet is preferably colorless and has a light transmittance of at least 80% or even 90% within the meaning of EN 410: 1998. The thickness of the glass sheet is preferably in a range from 0.1 to 6 mm, in particular from 0.3 to 3 mm. The glass sheet is coated on one of its faces with a layer comprising a vitreous material. Preferably, this layer is deposited in contact with the glass sheet. Advantageously, the layer covers at least 80%, especially 90% and even 95% of the surface of the glass sheet. According to one embodiment of the invention, the layer is advantageously made of vitreous material. In this case, and in order to obtain a diffusing substrate, it is preferable that the glass sheet diffuses the light (it may be in particular a satin glass, for example by an acid treatment), or that a layer The diffusing film is disposed beneath the layer comprising a vitreous material, in particular in contact with both the glass sheet and the layer made of the vitreous material. The diffusing aspect is thus not obtained by the layer itself. According to another embodiment of the invention, the layer comprising a vitreous material further comprises diffusing elements. The layer is even advantageously made of vitreous material and diffusing elements.

In this embodiment, the layer is itself diffusing, and it will be called diffusing layer. Preferably, the diffusing elements are chosen from particles and cavities. The diffusing layer 5 can contain both particles and cavities. The particles are preferably chosen from particles of alumina, zirconia, silica, titanium dioxide, calcium carbonate and barium sulfate. The diffusing layer may comprise a single type of particles, or several different types of particles. The cavities are preferably formed during cooking by removal of organic compounds, for example medium. They are preferably closed and not connected. The diffusing elements preferably have a characteristic dimension allowing diffusion of visible light, in particular between 200 nm and 5 μm. A characteristic dimension may be a median diameter. The mass concentration of particles in the diffusing layer is preferably in the range of 0.2 to 10%, especially 0.5 to 8%, and even 0.8 to 5%. The diffusing elements can be distributed homogeneously in the vitreous material. They may alternatively be heterogeneously distributed, for example by providing gradients. The diffusing layer may also consist of several elementary layers differentiating from each other by a different nature, size or proportion of scattering elements. The physical thickness of the layer comprising a vitreous material is preferably in a range from 0.5 to 100 μm, especially from 1 to 80 μm and more particularly from 2 to 60 μm, or even from 2 to 30 μm. Other layers may be deposited on the layer comprising a vitreous material, and in particular in contact with it. It may for example be a planarization layer, intended to cover any particles located on the surface of the layer comprising a vitreous material, in particular of the diffusing layer, so as to reduce the roughness of the latter. The planarization layer may for example consist of the vitreous material defined above, or of another vitreous material. A barrier layer, for example silica or silicon nitride, the thickness of which is in particular in a range from 5 to 30 nm, may be deposited on the layer comprising a glassy material or the planarization layer, in contact with it . By the use of the adjective "diffusing" to describe the substrate and, where appropriate, the glass sheet or the layer comprising a vitreous material, it is preferably understood that the blur is at least 40%, especially 50%, and even 60% or 70%, even 80%. The blur, sometimes called "veil" is measured by a Naze-meter according to ASTM D1003. The layer comprising a vitreous material is advantageously coated with an electroconductive layer. The latter is preferably in direct contact with the layer comprising a vitreous material, or optionally with the planarization layer or the barrier layer. The electroconductive layer is preferably based on a transparent conductive oxide (TC0), such as, for example, indium tin oxide (ITO). Other conductive materials are possible, for example silver layers or conductive polymers. The diffusing substrate may thus comprise (or consist of), by way of examples: a sheet of non-diffusing glass, then a diffusing layer consisting of the vitreous material and diffusing elements, then (optionally) a layer of planarization, then (optionally) a barrier layer, and finally an electroconductive layer, each layer mentioned being in direct contact with the layer which precedes it and the layer which follows it, - a sheet of non-diffusing glass, then a diffusing layer, then a layer consisting of vitreous material, then (optionally) a barrier layer, and finally an electroconductive layer, each layer mentioned being in direct contact with the layer which precedes it and the layer which follows it, - diffusing glass sheet, then a layer 20 made of vitreous material, then (optionally) a barrier layer, and finally an electroconductive layer, each layer mentioned being in direct contact with each other; with the layer that precedes it and the layer that follows it. In the organic light-emitting diode device according to the invention, the glass sheet coated with the layer comprising a vitreous material and the electroconductive layer (acting as a first electrode) is associated with an organic electroluminescent system in the form of at least one layer of organic material, itself coated with an electroconductive layer serving as a second electrode. The organic electroluminescent system is therefore located between the substrate and the second electrode, in direct contact with the first and the second electrode. The electroluminescent system is preferably composed of several layers: hole injection layer (for example polyethylene dioxythiophene doped with polystyrene sulfonic acid or copper phthalocyanine), hole transport layer (for example triphenylamine derivatives). ), emission layer (for example metal complexes of quinoline derivatives), electron transport layer (for example, oxadiazole, triazole, bathophenanthroline derivatives, etc.), injection layer of electrons (for example lithium or cesium) etc ... The OLED device according to the invention is preferably used as a source of polychromatic lighting, including white light. It is preferably a rear-emission device in the sense that light is emitted through the glass sheet. In this case, the second electrode consists of a reflective material, for example a metal film, in particular aluminum, silver, magnesium, etc., etc. Preferably, the OLED device therefore comprises successively a glass sheet, a layer comprising a vitreous material, optionally a barrier or planarization layer, an electroconductive layer (typically made of ITO), a multi-layer electroluminescent system and a reflecting electrode. The glass frit according to the invention is preferably obtained by melting raw materials and then forming the frit. The raw materials (oxides, carbonates, etc.) can be melted at temperatures of the order of 950 to 1100 ° C., and then the glass obtained can be cast, for example rolled between two rolls. The glass obtained can then be milled, for example in a ball mill, a jet mill, a ball mill, or an attritor mill. The glass frit is preferably in the form of particles whose d90 is at most 10 μm, in particular 5 μm, or even 4 μm. The particle size distribution can be determined using a laser granulometer. The layer comprising a vitreous material is preferably obtained by a process in which: - the glass frit according to the invention is mixed with an organic medium so as to form a paste, - said paste is deposited on the glass sheet, - we cook the whole. The organic medium is typically selected from alcohols, glycols, terpineol esters. The mass proportion of medium is preferably in a range from 10 to 50%. The deposition of the paste can be carried out in particular by screen-printing, by roll-coating, by dipping, by knife application, by spraying, by spinning, by vertical layering or by means of a slot-shaped die ( slot die coating). In the case of screen printing, a screen made of textile or metallic mesh is preferably used, lapping tools and a squeegee, the control of the thickness being ensured by the choice of the mesh of the screen and its tension, by the choice of the distance between the glass sheet and the screen, by the pressures and speeds of movement of the doctor blade. The deposits are typically dried at a temperature of 100 to 150 ° C by infrared or ultraviolet radiation depending on the nature of the medium. The firing is preferably carried out in an oven at a temperature in a range from 500 to 600 ° C, especially from 510 to 580 ° C. The electroconductive layer may be deposited by various thin-film deposition techniques, such as, for example, cathodic sputtering techniques, in particular magnetic-field assisted (magnetron-process), chemical vapor deposition (CVD), in particular assisted by plasma (PECVD, APPECVD), or liquid deposit. The following examples illustrate the invention in a non-limiting manner.

Different glass frits were obtained by melting raw materials. To do this, sufficient raw materials were carried to obtain 300 g of glass for 1:30 at a temperature of 1000 ° C in crucibles heated by Joule effect of 400 cm3.

Tables 3, 4 and 5 summarize the results obtained. In these tables are indicated: - the chemical composition of the frit (in weight percent of oxide), - the glass transition temperature, denoted "Tg" and expressed in ° C, - the crystallization temperature, denoted T. and expressed in ° C. the coefficient of linear thermal expansion, denoted a and expressed in 10-7 / K, the refractive index for a wavelength of 550 nm, denoted n, measured by ellipsometry, the light absorption for a thickness; of 3 mm, denoted AL, measured by spectrophotometry. Like Tg, T. is measured by differential scanning calorimetry.

Examples 1 to 10 (Tables 3 and 4) are examples according to the invention, while Examples C1 to C5 are comparative examples. These comparative examples devitrify too easily to be shaped vitreous material, hence their very high light absorption.

1 2 3 4 5 Bi203 73.1 74.5 73.7 72.3 72.4 ZnO 5.54 5.31 5.39 9.34 7.9 SiO2 7.9 7.7 7.9 7.6 9.4 B2O3 7.71 7.8 7.74 6.31 6.86 A1203 2.5 2.5 2.4 2.4 2.5 Na2O 0.1 0.11 0.11 0.1 0, 08 Ca0 3,1 0 1,7 1,9 0,04 MgO 0 2 1 0 0 Mg0 + ZnO 5,54 7,31 6,39 9,34 7,9 MgO + CaO 3,1 2 2,7 1 0.04 Tg (° C) 460 468 464 456 455 T. (° C) 693 678 668 a (10-7 / K) 88.7 82.2 84.2 84.9 77.5 n 1 91 1.93 1.93 1.92 1.90 AL (%) 9.4 7.3 10.3 11.1 7.4 Table 3 6 7 8 9 10 Bi203 72 74.8 75.9 77.2 77 ZnO 4.87 2.68 0.08 4.51 2.51 SiO2 11.4 9.2 8.4 7.4 7.8 B2O3 8.37 8.36 10.4 6.18 9.46 A1203 2.7 2.7 2.6 2.3 2.4 Na2O 0.09 0.08 0.09 0.09 0.09 CaO 0 0 0 0 0 MgO 0 2.1 2.1 1.9 1 MgO + ZnO 4.87 4.78 2.18 6.41 3.51 MgO + CaO 0 2.1 2.1 1.9 1 Tg (° C) 457 475 478 475 458 T. (° C) 682 678 683 677 668 a (10-7 / K) 76.9 77.1 86.4 77.2 82.9 AL (%) 8.3 10.5 8.5 7.3 8.1 n 1.89 1, 91 1.89 1.96 1.92 Table 4 Cl C2 C3 C4 C5 Bi203 71.9 72.7 72.5 72.2 72.3 ZnO 10.7 10.7 10.4 9.87 9.23 SiO2 7.8 7.6 7.6 7.6 6.8 B2O3 5.62 5.7 5.8 6.58 6.29 A1203 2.5 2.4 2.4 2.5 2.6 Na2O 0.1 0.09 0.11 0.1 0.1 CaO 1.4 0 0.7 0 1 MgO 0 0.9 0.4 1.2 0.6 MgO + ZnO 10.7 11 , 6 10.8 11.07 9.83 MgO + CaO 1.4 0.9 1.1 1.2 1.6 AL (%) 24.5 28.6 22.4 22.9 15.8 Table 55

Claims (12)

REVENDICATIONS1. A diffusing substrate for an organic light-emitting diode device comprising a glass sheet coated on one of its faces with a layer comprising a vitreous material, such that said vitreous material has a chemical composition comprising the following constituents, varying within the weight limits hereinafter defined: Bi203 60-85% B203 5-12% SiO2 6-20% Mg0 + ZnO 0-9.5% A1203 0-5% Li20 + Na2O + K20 0-5% Ca0 0-5% Ba0 0-20% . 2. Diffuser substrate according to the preceding claim, such that the weight content of Bi 2 O 3 is in a range from 65 to 80%, especially from 68 to 75%. 3. Diffuser substrate according to one of the preceding claims, such that the weight content of ZnO is at most 8%, in particular is less than 5%. 25 4. Diffuser substrate according to one of the preceding claims, such that the weight content of SiO 2 is in a range from 7 to 12%. 5. diffusing substrate according to one of the preceding claims, such that the sum of the weight contents Mg0 30 and ZnO is in a range from 2 to 9%. 6. diffusing substrate according to one of the preceding claims, such that the sum of Ca0 and Mg0 weight contents is in a range from 0.5 to 4%. 7. Diffuser substrate according to one of the preceding claims, such that the layer comprising a vitreous material further comprises diffusing elements selected from particles and cavities. 8. Substrate according to the preceding claim, such that the particles are chosen from particles of alumina, zirconia, silica, titanium dioxide, calcium carbonate and barium sulfate. 9. Substrate according to one of claims 1 to 6, such that the layer comprising a vitreous material is made of said vitreous material, and such that the glass sheet diffuses light or a diffusing layer is disposed under the layer comprising a vitreous material. 10. Diffuser substrate according to one of the preceding claims, such that an electroconductive layer is disposed on the layer comprising a vitreous material. 20 11. Organic electroluminescent diode device comprising a diffusing substrate according to the preceding claim. 12. Glass frit whose chemical composition comprises the following constituents, varying within the weight limits defined below: Bi 2 O 3 60-85% B 2 O 3 5-12% SiO 2 6-20% MgO + ZnO 0-9.5% A1203 0-5% 21 Li2O + Na2O + K20 0-5% - Ca0 0-5% - BaO 0-20% .5