JP5013304B2 - Glass substrate for display - Google Patents

Description

  The present invention relates to a glass substrate for a display used in a flat panel display such as a liquid crystal, a plasma display, a field emission display and an inorganic EL (electroluminescence) display, and more particularly to a glass substrate suitable as a back plate of an inorganic EL display. It is.

  Inorganic EL displays have many advantages, such as being thin and light, clear display, easy image miniaturization, high-quality images, and full color. Tend to.

  For example, as shown in FIG. 1, the inorganic EL display has a metal electrode 11, a first dielectric layer 12, an inorganic EL light emitter layer 13, a second dielectric layer 14, an ITO electrode 15 on a back substrate 10. The color conversion layer 16 and the front substrate 17 are stacked in order.

  The inorganic EL display having such a structure generates light by applying voltage to the metal electrode 11 and the ITO electrode 15 to excite the inorganic EL light emitting layer 13, and color-converts the light by the color conversion layer 16. It is like that.

  In recent years, attempts have been made to use inorganic EL displays for home televisions and the like, and a substrate having a size of about 40 to 60 type is required for large displays. Even when producing a 12-inch or smaller display, it is much more efficient to produce a large substrate once and then cut it into multiple pieces rather than making a back substrate for each piece. In view of this, it is desired to increase the size of the substrate.

Conventionally, in order to form a dielectric layer and a phosphor layer on a back substrate in a manufacturing process of an inorganic EL display, these materials are applied to the back substrate by a paste method or the like, dried, and then fired at about 800 ° C. The method is taken. Therefore, an alumina substrate having high heat resistance is mainly used as the back substrate.
Japanese Unexamined Patent Publication No. 7-50197 JP 2003-157972 A

However, it is very difficult to produce a large substrate from alumina, and there is a problem that the cost becomes extremely high. Moreover, since the alumina substrate has a large density of about 4 g / cm ^3, it is a great obstacle when reducing the weight of the inorganic EL display.

  Under such circumstances, the use of a glass substrate as a back substrate has been studied. Therefore, it was first considered to use a soda lime glass substrate used for the front substrate of the inorganic EL display. The glass substrate is inexpensive, can be formed into a large plate shape, and has a low density. However, a soda lime glass substrate has low heat resistance, and if it is baked at a high temperature of 800 ° C., it causes thermal deformation and cannot be used as a back substrate.

  In recent years, in order to reduce the production cost of inorganic EL displays, the firing temperature has been lowered, and a technique for forming a uniform dielectric layer or light emitting layer at a temperature of about 650 to 700 ° C. has been developed and is satisfactory. It is now possible to produce color purity displays. However, even under such firing conditions, if a soda lime glass substrate is used as the back substrate, thermal deformation is still caused. If a soda lime glass substrate is used for the back substrate, the dielectric layer and the light emitting layer must be fired at a temperature of 650 ° C. or lower, that is, a temperature at which the glass substrate is not thermally deformed. In baking, a uniform dielectric layer or light-emitting layer cannot be obtained, and the color purity of the inorganic EL display is remarkably deteriorated and cannot be used.

Further, since various films are formed on the inorganic EL display back substrate, it is desirable that the thermal expansion coefficient of the substrate is 60 to 90 × 10 ⁻⁷ / ° C. so as to match these thermal expansion coefficients. It is. In order to obtain such a high thermal expansion coefficient, the content of the alkali metal oxide may be increased. However, if the content of the alkali metal oxide is excessively increased, the strain point is lowered and the heat resistance of the glass is decreased. Damaged.

  The object of the present invention has been made in view of the above circumstances, and thermal expansion does not occur even when baked at 650 to 700 ° C., and is consistent with the thermal expansion coefficient of various films formed on the glass substrate. It is to provide a glass substrate for a display having a coefficient and capable of being reduced in weight and size.

A glass substrate for displays according to the invention, by mass _{percentage, SiO 2 50~ 70%, Al} 2 O 3 4~13%, B 2 O 3 0~10%, 0~10% MgO, CaO 0~10%, _{SrO 5~15%, BaO 0~4, Na} 2 O 0~2%, K 2 O 9~13%, characterized in that it contains ZrO 2 5 to 15%.

  Since the glass substrate of the present invention has a high strain point, thermal deformation can be suppressed in a heat process when manufacturing the display. Moreover, since it has a thermal expansion coefficient that matches the peripheral material, thermal stress generated between the peripheral material and the glass substrate can be suppressed. Further, the low density can reduce the weight, and since the liquidus temperature is low, a large substrate can be manufactured at low cost. Therefore, it is suitable as a glass substrate for a display used for a flat panel display, particularly as a glass substrate for a back plate of an inorganic EL display.

In general, an aluminosilicate glass substrate tends to have a low thermal expansion coefficient when the strain point is increased in order to suppress thermal deformation in a heat process in manufacturing a display. It becomes difficult to match the thermal expansion coefficient of the film, and thermal stress is likely to occur between these peripheral materials and the glass substrate. However, the glass substrate for display of the present invention is composed of Al ₂ O ₃ and ZrO ₂ that are components that increase the strain point in glass, and K ₂ O that is a component that increases the thermal expansion coefficient without significantly reducing the strain point. Is contained as an essential component. Therefore, it can have a high strain point and a thermal expansion coefficient that matches the surrounding material, suppresses thermal deformation of the glass substrate in the thermal process when manufacturing the display, and occurs between the surrounding material and the glass substrate. Thermal stress can be suppressed.

Further, when the content of ZrO _{2 in} the glass is increased, devitrification caused by ZrO ₂ is generated and the formability tends to be remarkably lowered, but Al ₂ O ₃ and SrO are contained as essential components, By adjusting the content of these components, it is possible to suppress the generation of devitrified materials due to ZrO ₂ .

  In addition, it is preferable that a strain point is 630 degreeC or more in order to prevent the heat deformation of a glass substrate at the heat process at the time of manufacturing a display. When the strain point is lowered, thermal deformation is likely to occur in the thermal process when manufacturing the display. More preferably, it is 640 degreeC or more, More preferably, it is 650 degreeC or more, Especially preferably, it is 660 degreeC or more, Most preferably, it is 670 degreeC or more.

Moreover, in order to suppress the thermal stress which generate | occur | produces between a peripheral material and a glass substrate, it is preferable that the thermal expansion coefficient in 30-380 degreeC is 60-90 * 10 < ^-7 > / degreeC. If the thermal expansion coefficient is too large or too small, it becomes difficult to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate. A more preferred range is 60 to 80 × 10 ⁻⁷ / ° C., and even more preferred is 65 to 75 × 10 ⁻⁷ / ° C.

In order to reduce the weight of the display, the density is preferably low, and is preferably 2.80 g / cm ³ or less. More preferably 2.75 g / cm ³ or less, more preferably 2.70 g / cm ³ or less, most preferably 2.65 g / cm ³ or less.

Furthermore, in order to produce a large glass substrate at a low cost and in large quantities, it is necessary to have excellent formability, and it is preferable that the liquidus temperature is low and the liquidus viscosity is high. The liquidus temperature is preferably 1250 ° C. or less, more preferably 1200 ° C. or less, further preferably 1150 ° C. or less, particularly preferably 1100 ° C. or less, and most preferably 1050 ° C. or less. The liquid phase viscosity is preferably 10 ^4.5 dPa · s or more, more preferably 10 ^4.8 dPa · s or more, further preferably 10 ^5.0 dPa · s or more, and particularly preferably 10 ^5.3 dPa · s or more. Preferably, it is 10 ^5.5 dPa · s or more. In particular, by setting the liquid phase viscosity as described above, it is possible to form into plate glass by the slot down draw method, overflow down draw method, float method, redraw method, roll out method, etc., which are well known plate glass forming methods. Thus, a large amount of a large glass substrate can be obtained at a low cost.

In order to melt the glass satisfactorily, the temperature of the glass melt at a viscosity of 10 ^2.5 dPa · s is preferably low, and is preferably 1600 ° C. or lower. More preferably, it is 1590 degrees C or less, More preferably, it is 1580 degrees C or less.

  The reason why the ratio of each component is limited as described above in the glass substrate for display of the present invention will be described below.

SiO ₂ is a component that forms a network of glass. When the content is less than 50%, the glass strain point tends to decrease, and the glass substrate is likely to be thermally deformed or the thermal expansion coefficient becomes too large in the thermal process when manufacturing the display device. It becomes difficult to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate. On the other hand, if the content exceeds 70 %, devitrification due to SiO ₂ is generated or the high temperature viscosity of the glass tends to be high, and melting and molding become difficult. In addition, the thermal expansion coefficient becomes too small to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate. The preferred range of SiO ₂ is 53-70%, more preferably 53-65%, more preferably 54-60%, particularly preferably 55 to 58%.

Al ₂ O ₃ is a component that increases the strain point of the glass and suppresses the generation of devitrified materials due to ZrO ₂ . If the content is less than 4%, the glass substrate is easily deformed due to the lowering of the glass strain point and the display device is manufactured, and devitrified materials due to ZrO ₂ are generated. It becomes easy. On the other hand, if the content exceeds 13%, devitrified materials due to Al ₂ O ₃ are generated or the high-temperature viscosity of the glass tends to increase, and melting and molding become difficult. A preferable range of Al ₂ O ₃ is 5 to 10%, more preferably 5 to 9%, still more preferably 5 to 8%, and particularly preferably 6 to 8%.

B ₂ O ₃ is a component that lowers the high-temperature viscosity of the glass to improve the meltability and moldability of the glass and suppress devitrification. If the content exceeds 10%, the strain point of the glass tends to decrease, and the glass substrate is likely to be thermally deformed in the heat process when manufacturing the display device. A preferable range of B ₂ O ₃ is 0 to 8%, more preferably 0 to 5%, still more preferably 0 to 4%, and particularly preferably 0 to 2%.

MgO is a component that lowers the high temperature viscosity of the glass to improve the meltability and moldability of the glass and adjust the thermal expansion coefficient. If the content exceeds 10%, the thermal expansion coefficient becomes too large to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate, and the density is low. As a result, it becomes difficult to reduce the weight of the display. Further, devitrification due to ZrO ₂ or MgO tends to occur, and molding becomes difficult. The preferable range of MgO is 0 to 8%, more preferably 0 to 6%, still more preferably 0 to 4%, and particularly preferably 0 to 3%.

CaO is a component that lowers the high-temperature viscosity of the glass to improve the meltability and moldability of the glass and adjust the thermal expansion coefficient. If the content exceeds 10%, the thermal expansion coefficient becomes too large to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate, and the density is low. As a result, it becomes difficult to reduce the weight of the display. Further, devitrification caused by ZrO ₂ or CaO is remarkably generated, and molding becomes difficult. The preferable range of CaO is 0 to 8%, more preferably 0 to 6%, still more preferably 0 to 4%, and particularly preferably 0 to 2%.

SrO is a component that lowers the high-temperature viscosity of the glass to improve the meltability and moldability of the glass and adjust the thermal expansion coefficient. Further, a component to suppress the generation of devitrification due to ZrO _2. If the content is less than 5%, the effect is difficult to obtain. On the other hand, if the content is more than 15%, the thermal expansion coefficient becomes too large and it becomes difficult to match the thermal expansion coefficient of the peripheral material, and thermal stress is easily generated between the peripheral material and the glass substrate, or the density is increased. As a result, it becomes difficult to reduce the weight of the display. Further, devitrification due to SrO tends to occur, and molding becomes difficult. A preferable range of SrO is 6 to 14%, more preferably 8 to 13%, still more preferably 9 to 12%, and particularly preferably 10 to 11%.

BaO is a component that lowers the high-temperature viscosity of the glass and improves the meltability and formability of the glass and adjusts the thermal expansion coefficient without devitrifying the glass as compared with MgO and CaO. If the content exceeds 8%, the thermal expansion coefficient becomes too large to match the thermal expansion coefficient of the peripheral material, and thermal stress is likely to occur between the peripheral material and the glass substrate, and the density is low. As a result, it becomes difficult to reduce the weight of the display. In addition, the strain point of the glass tends to be remarkably lowered, and the glass substrate is likely to be thermally deformed in a heat process when manufacturing the display device. The BaO of range is from 0 4%, preferably in the al is 1-4%, particularly preferably 1.5 to 3%.

Na ₂ O is a component that lowers the high-temperature viscosity of the glass and improves meltability and moldability. It is also a component that adjusts the thermal expansion coefficient of glass. If the content exceeds 6%, the strain point of the glass tends to be remarkably lowered, and the glass substrate is likely to be thermally deformed or the thermal expansion coefficient becomes too large in the thermal process when manufacturing the display device. Therefore, it becomes difficult to match the thermal expansion coefficient of the peripheral material, and thermal stress is easily generated between the peripheral material and the glass substrate. Na ₂ O in the range is from 0 to 2%, particularly preferably 0 to 1%.

K ₂ O is a component that adjusts the thermal expansion coefficient without significantly reducing the strain point of the glass. When the content is less than 7%, the thermal expansion coefficient tends to be small, and it becomes difficult to match the thermal expansion coefficient of various films formed on the glass substrate. Thermal stress is likely to occur. On the other hand, when the content exceeds 15%, the strain point of the glass tends to decrease, and the glass substrate is likely to be thermally deformed or the thermal expansion coefficient becomes too large in the thermal process when manufacturing the display device. Therefore, it becomes difficult to match the thermal expansion coefficient of the peripheral material, and thermal stress is easily generated between the peripheral material and the glass substrate. K ₂ O in the range is 9-13%, more preferably 10 to 13%, particularly preferably 11 to 12%.

ZrO ₂ is a component that increases the strain point of glass. When the content is less than 5%, the strain point of the glass tends to be remarkably lowered, and the glass substrate is likely to be thermally deformed in a heat process when manufacturing the display device. On the other hand, when the content exceeds 15%, devitrified materials due to ZrO ₂ are likely to be generated. Further, the density increases and it becomes difficult to reduce the weight of the display. The preferable range of ZrO ₂ is 6 to 13%, more preferably 7 to 10%, still more preferably 7 to 9%, and particularly preferably 7 to 8%.

Note that in the glass system which contains a ZrO ₂ 5% or more in order to increase the strain point of the glass, to prevent the occurrence of devitrification due to non devitrification thereof and ZrO ₂ due to ZrO ₂ is, Al ₂ The O ₃ / ZrO ₂ value is adjusted to be 0.5 to _2.5 , the SrO / ZrO ₂ value is adjusted to be 0.5 to 2.0, the CaO / ZrO ₂ value is It is preferable to adjust so that a value may be set to 0-1.0.

When the value of Al ₂ O ₃ / ZrO ₂ becomes small, devitrification materials due to ZrO ₂ tend to be generated, and molding becomes difficult. On the other hand, when the value of Al ₂ O ₃ / ZrO ₂ is increased, devitrification due to Al ₂ O ₃ tends to occur, and molding becomes difficult. A more preferable range of Al ₂ O ₃ / ZrO ₂ is 0.5 to 1.5, more preferably 0.6 to 1.0, and particularly preferably 0.7 to 0.9.

Moreover, when the value of SrO / ZrO ₂ becomes small, it becomes difficult to obtain the effect of suppressing the generation of devitrified materials due to ZrO ₂ . On the other hand, when the value of SrO / ZrO ₂ increases, devitrification due to SrO tends to occur and molding becomes difficult. A more preferable range of SrO / ZrO ₂ is 0.7 to 1.5, more preferably 1.0 to 1.4, and particularly preferably 1.1 to 1.3.

Furthermore, when the value of CaO / ZrO ₂ increases, devitrification due to CaO or ZrO ₂ tends to occur remarkably, making molding difficult. The more preferable range of CaO / ZrO ₂ is 0 to 0.7, more preferably 0 to 0.5, and particularly preferably 0 to 0.3.

  In the present invention, in addition to the above components, the following components may be added.

  ZnO may be added up to 10%, preferably up to 8%, more preferably up to 5% in order to reduce the viscosity of the glass and improve the meltability and moldability. In addition, since there exists a tendency for a density to become large or a strain point to fall when content of ZnO increases, it is desirable to suppress an addition amount to 10% or less.

Nb ₂ O ₅ , WO ₃ , Ta ₂ O ₅ in a total amount of up to 10%, preferably 8% in order to increase the strain point of the glass and lower the high temperature viscosity of the glass to improve the meltability and formability. Up to 5%, more preferably up to 5%. In addition, since the density will increase as the total amount of these components increases, it is desirable to suppress the addition amount to 10% or less in the total amount.

In order to suppress devitrification of the glass, P ₂ O ₅ may be added up to 3%, preferably up to 2%, more preferably up to 1%. Incidentally, so the more the content of P ₂ O _5, it becomes likely to undergo phase separation, it is desirable to suppress the addition amount below 3%.

TiO ₂ may be added up to 10%, preferably up to 5%, more preferably up to 3% in order to suppress the coloring of the glass by ultraviolet rays or to increase the chemical durability. Incidentally, the content of TiO ₂ increases, because of the tendency of the glass is colored, it is desirable to suppress the addition amount to 10% or less.

In order to suppress the coloring of the glass by the electron beam, CeO ₂ may be added up to 5%, preferably up to 3%, more preferably up to 2%. Incidentally, the content of CeO ₂ is increased, because of the tendency of the glass is colored, it is desirable to suppress the addition amount below 5%.

Further, As ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ , SO ₃ , F, Cl, etc. can be added up to 3% as clarifiers. In the case of molding by the float process, As ₂ O ₃ and Sb ₂ O ₃ are reduced in the float bath to become metal foreign matter, so introduction should be avoided, and SO ₃ should be contained at 20 ppm or more. preferable. In the case of molding by the overflow down draw method, it is preferable to contain 0.1 to 3% of Sb ₂ O ₃ , SnO ₂ and Cl in total, and particularly 0.05 to ₂ of Sb ₂ O ₃ . %, SnO ₂ is preferably contained in an amount of 0.01 to 1%, and Cl is preferably contained in a proportion of 0.005 to 1%. As ₂ O ₃ has a useful clarification effect, but it is desirable to avoid introduction from an environmental point of view. In addition, as raw materials for As ₂ O ₃ and Sb ₂ O ₃ , trioxide (As ₂ O ₃ , Sb ₂ O ₃ ), pentoxide (As ₂ O ₅ , Sb ₂ O ₅ ) and the like are used as raw materials. Can do.

  Next, the manufacturing method of the glass substrate for displays of this invention is demonstrated.

  First, a glass raw material is prepared so that it may become said glass composition range. Subsequently, the prepared glass raw material is put into a continuous melting furnace, heated and melted, defoamed, then supplied to a forming apparatus, formed into a plate shape, and slowly cooled to obtain a glass substrate.

  In addition, as a glass substrate forming method, there are various forming methods such as a slot down draw method, an overflow down draw method, a float method, a redraw method, etc., but it is formed into a plate shape by the down draw method, particularly the overflow down draw method. It is preferable to do. The reason is that, in the case of the overflow downdraw method, unlike other molding methods, the surface of the glass substrate does not come into contact with the molded body, and thus has a glass surface without a contaminated part and is not polished. This is because a glass substrate having a high surface quality can be obtained, and a large glass substrate can be easily obtained at a relatively low cost.

  In addition, the inorganic EL display is formed by sequentially forming a metal electrode and a dielectric layer on the glass substrate obtained as described above by a printing method or the like, and then a light emitting layer by a sputtering method or a vapor deposition method or the like thereon. In addition, a dielectric layer and a transparent electrode are formed in this order, and further, a back substrate on which a color conversion layer is formed by photolithography or the like and a front substrate are bonded together. As the front substrate, either a soda lime glass substrate or the glass substrate of the present invention may be used.

  Hereinafter, the present invention will be described based on examples.

  Tables 1 and 2 show examples of the present invention.

  Each sample in the table was prepared as follows.

  First, the glass raw material was prepared so that it might become the composition of a table | surface, and it melted at 1500-1600 degreeC for 6 hours using the platinum pot. Thereafter, the molten glass is poured onto a carbon plate, formed into a plate shape, slowly cooled, then polished on both sides so that the plate thickness becomes 0.7 mm, and the obtained plate glass is cut into a size of 200 mm square. Sample glass was produced by processing.

For each of the samples thus obtained, the glass melt temperature, liquidus temperature and liquidus viscosity corresponding to the viscosities of density, thermal expansion coefficient, strain point, softening point, 10 ⁴ and 10 ^2.5 dPa · s are determined. It was measured. The results are shown in the table.

As is apparent from the table, sample No. Each of the samples 1 to 9 has a strain point of 658 ° C. or higher, and can suppress thermal deformation of the glass substrate in the heat treatment step. Moreover, it has a thermal expansion coefficient of 62 to 75 × 10 ⁻⁷ / ° C., and has a thermal expansion coefficient that matches well with the surrounding materials, so that the generation of thermal stress can be suppressed. Furthermore, the temperature of the glass melt corresponding to a viscosity of 10 ^2.5 dPa · s is as low as 1594 ° C. or less, and the melt property is excellent, and the temperature of the glass melt corresponding to a viscosity of 10 ⁴ dPa · s is 1350 ° C. or less. The phase temperature was 1245 ° C. or lower, and the moldability was excellent. Further, the liquid phase viscosity is as high as 10 ⁴ dPa · s or more, and a large-sized glass substrate can be produced in large quantities at a low cost.

  The density was measured by a well-known Archimedes method.

  Regarding the thermal expansion coefficient, each obtained sample was remelted to prepare a columnar sample having a diameter of 5.0 mm and a length of 20 mm, and an average thermal expansion coefficient at 30 to 380 ° C. was measured with a dilatometer.

  The viscosity of the glass was measured as follows.

  For the strain point, each sample obtained was remelted to produce a columnar sample with a diameter of 8.0 mm and a length of 100 mm, and then processed into a fiber shape by the redraw method based on ASTM C336-71 did. In addition, the higher this temperature is, the more the thermal deformation and thermal shrinkage of the glass substrate in the thermal process when manufacturing the display device can be suppressed.

  As for the softening point, a cylindrical sample processed into a fiber shape by the redraw method was measured based on ASTM C336-93 in the same manner as the strain point measurement sample.

The glass melt temperature corresponding to a glass viscosity of 10 ⁴ and 10 ^2.5 dPa · s was measured by a platinum ball pulling method. Note that the temperature of the glass melt corresponding to 10 ⁴ dPa · s is a guideline for forming the glass into a plate shape, and the lower the temperature, the better the moldability. Further, the temperature of the glass melt corresponding to 10 ^2.5 dPa · s is a guideline for melting the glass, and the lower the temperature, the better the meltability.

  The liquid phase temperature was measured as follows. First, each sample was pulverized and mixed to a size of 300 to 500 μm, placed in a platinum boat, transferred to a temperature gradient furnace at 980 to 1300 ° C. and held for 24 hours. I took out the boat. Thereafter, the glass was taken out from the platinum boat. The sample thus obtained was observed with a polarizing microscope, and the crystal precipitation point was measured.

  For the liquid phase viscosity, a viscosity curve was created from the viscosity measured by the above method, and the viscosity corresponding to the liquid phase temperature was determined from the viscosity curve.

  The display glass substrate of the present invention is not limited to inorganic EL display applications, and can be used, for example, for liquid crystal, plasma display, and field emission display applications.

It is explanatory drawing which shows the structure of an inorganic EL display.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Back substrate 11 Metal electrode 12 1st dielectric layer 13 Inorganic EL light emitting layer 14 2nd dielectric layer 15 ITO electrode 16 Color conversion layer 17 Front substrate

Claims (11)

By mass _{percentage, SiO 2 50~ 70%, Al} 2 O 3 4~13%, B 2 O 3 0~10%, 0~10% MgO, CaO 0~10%, SrO 5~15%, BaO 0~ A glass substrate for display, comprising 4%, Na ₂ O 0 to 2%, K ₂ O 9 to 13%, and ZrO ₂ 5 to 15%. Al ₂ O ₃ / glass substrate for a display according to claim 1, wherein the ZrO ₂ is 0.5 to 2.5. A glass substrate for a display according to claim 1 or 2, wherein the CaO / ZrO ₂ is 0 to 1.0. A glass substrate for a display according to any one of claims 1 to 3, wherein the SrO / ZrO ₂ is 0.5 to 2.0.   The glass substrate for display according to any one of claims 1 to 4, wherein the strain point is 630 ° C or higher. The glass substrate for a display according to any one of claims 1 to 5, wherein the density is 2.80 g / cm ³ or less. The thermal expansion coefficient in 30-380 degreeC is 60-90 * 10 < ^-7 > / degreeC, The glass substrate for displays in any one of Claims 1-6 characterized by the above-mentioned. The glass substrate for display according to any one of claims 1 to 7, wherein the temperature of the glass melt corresponding to a viscosity of 10 ^2.5 dPa · s is 1600 ° C or lower.   Liquid crystal temperature is 1250 degrees C or less, The glass substrate for displays in any one of Claims 1-8 characterized by the above-mentioned. Liquid crystal viscosity is 10 < ^4.5 > dPa * s or more, The glass substrate for displays in any one of Claims 1-9 characterized by the above-mentioned. The glass substrate for display according to any one of claims 1 to 10, which is used as a back plate of an inorganic EL display.

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