阅读说明：本技术 一种无碱铝硼硅酸盐玻璃 (Alkali-free aluminoborosilicate glass ) 是由 彭寿 张冲 沈玉国 曹志强 金良茂 朱明柳 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种无碱铝硼硅酸盐玻璃,其特征在于由以下重量百分比的原料制成：60-72％的SiO<Sub>2</Sub>、13-18％的Al<Sub>2</Sub>O<Sub>3</Sub>、8.5-10%的B<Sub>2</Sub>O<Sub>3</Sub>、1-4.5％的MgO、3-8％的CaO、1-5％的SrO、0.5-2%ZrO<Sub>2</Sub>、1-5%的P<Sub>2</Sub>O<Sub>5</Sub>、0.1-0.5%的SnO<Sub>2</Sub>；其中SiO<Sub>2</Sub>+Al<Sub>2</Sub>O<Sub>3</Sub>为76-85%；(MgO+CaO+SrO)/Al<Sub>2</Sub>O<Sub>3</Sub>为0.4-0.7%；碱土金属氧化物总量为5-11.5%；B<Sub>2</Sub>O<Sub>3</Sub>/(B<Sub>2</Sub>O<Sub>3</Sub>+ZrO<Sub>2</Sub>+P<Sub>2</Sub>O<Sub>5</Sub>)为0.6-0.9%；(ZrO<Sub>2</Sub>+P<Sub>2</Sub>O<Sub>5</Sub>)/(MgO+CaO+SrO)为0.15-0.8%。有益效果：本发明的玻璃具有较高的应变点、高杨氏模量、高硬度、高比模数、合适的热膨胀系数、低热收缩率等特性,硼挥发率低至5.6-10.5%,有效控制住硼挥发带来的成分不均的现象；适于浮法成型工艺,不含As<Sub>2</Sub>O<Sub>3</Sub>、Sb<Sub>2</Sub>O<Sub>3</Sub>等有毒物质,对环境友好,适合于大规模工业生产；特别适于合LCD/OLED显示器用玻璃基板。(The invention relates to alkali-free aluminoborosilicate glass which is characterized by being prepared from the following raw materials in percentage by weight: 60-72% SiO 2 13-18% of Al 2 O 3 8.5-10% of B 2 O 3 1-4.5% of MgO, 3-8% of CaO, 1-5% of SrO and 0.5-2% of ZrO 2 1-5% of P 2 O 5 0.1-0.5% of SnO 2 (ii) a Wherein SiO is 2 +Al 2 O 3 76-85%; (MgO + CaO + SrO)/Al 2 O 3 0.4-0.7%; the total content of alkaline earth metal oxide is 5-11.5%; b is 2 O 3 /(B 2 O 3 +ZrO 2 +P 2 O 5 ) 0.6-0.9%; (ZrO) 2 +P 2 O 5 ) 0.15-0.8% of (MgO + CaO + SrO). Has the advantages that: the glass of the invention has higher strainThe material has the characteristics of point, high Young modulus, high hardness, high specific modulus, proper thermal expansion coefficient, low thermal shrinkage and the like, the boron volatilization rate is as low as 5.6-10.5%, and the phenomenon of component nonuniformity caused by boron volatilization is effectively controlled; is suitable for float forming process, and contains no As 2 O 3 、Sb 2 O 3 And the like, is environment-friendly and is suitable for large-scale industrial production; is particularly suitable for glass substrates for LCD/OLED displays.)

1. The alkali-free aluminoborosilicate glass is characterized by being prepared from the following raw materials in percentage by weight: 60-72% SiO₂13-18% of Al₂O₃8.5-10% of B₂O₃1-4.5% of MgO, 3-8% of CaO, 1-5% of SrO and 0.5-2% of ZrO₂1-5% of P₂O₅0.1-0.5% of SnO₂；

Wherein SiO is₂+Al₂O₃76-85%;

(MgO+CaO+SrO)/Al₂O₃0.4-0.7%;

the total content of alkaline earth metal oxide is 5-11.5%;

B₂O₃/(B₂O₃+ZrO₂+P₂O₅) 0.6-0.9%;

(ZrO₂+P₂O₅) 0.15-0.8% of (MgO + CaO + SrO).

2. The alkali-free aluminoborosilicate glass according to claim 1, which is prepared fromThe raw materials with the following weight percentages are as follows: 61.8-70.5% SiO₂13-17.5% of Al₂O₃8.5-10% of B₂O₃1 to 4.02 percent of MgO, 3.05 to 6.2 percent of CaO, 1.05 to 4.4 percent of SrO and 0.5 to 1.96 percent of ZrO₂1-4.93% of P₂O₅0.1-0.5% of SnO₂；

Wherein SiO is₂+Al₂O₃77.4-83.5%;

(MgO+CaO+SrO)/Al₂O₃0.42-0.65%;

the total content of alkaline earth metal oxide is 5.45-10.3%;

B₂O₃/(B₂O₃+ZrO₂+P₂O₅) 0.62-0.83%;

(ZrO₂+P₂O₅) 0.15-0.7% of (MgO + CaO + SrO).

3. The alkali-free aluminoborosilicate glass according to claim 1 or 2, wherein the glass composition has an β -OH number of less than 0.5%, a boron volatility of less than 11%, and a coefficient of thermal expansion in the range of 50 ℃ to 350 ℃ of less than 39.5 × 10^-7/° C, Young's modulus higher than 78GPa, strain point higher than 690 ℃, melting temperature lower than 1662 ℃ and thermal shrinkage lower than 11.5 ppm.

4. The alkali-free aluminoborosilicate glass according to claim 1 or 2, wherein the glass composition has an β -OH value of 0.11 to 0.47%, a boron volatility of 5.67 to 10.37%, and a coefficient of thermal expansion in the range of 50 to 350 ℃ of 33.70 to 39.5 × 10^-7The Young modulus is 78.2-84.1GPa, the strain point is 690-739 ℃, the melting temperature is lower than 1662 ℃, and the thermal shrinkage rate is 7.68-11.45 ppm.

Technical Field

The invention belongs to the field of glass production, relates to various glass substrates for displays, and particularly relates to alkali-free aluminoborosilicate glass.

Background

With the development of the electro-optical display technology and the popularization of electronic products, the liquid crystal display is continuously updated, the performance requirements of people on the display are continuously improved, and the display market is gradually occupied by the lightness, thinness, high resolution and ultra high definition, so that the liquid crystal display becomes a mainstream characteristic. Therefore, the technology of the glass substrate for the display is also continuously updated, so that the characteristic requirements of the glass substrate are more and more strict. In the process of manufacturing a flat panel display panel, a metal or oxide film needs to be plated on the surface of a glass substrate, alkali metal ions in the substrate glass diffuse into the film to damage the film characteristics, and the glass does not contain alkali metal oxide. With the increasing resolution of display images, the deformation of the glass substrate is required to be lower and lower during the thermal treatment process of panel printing and coating, and the thermal shrinkage rate of the glass substrate needs to be strictly controlled.

The amorphous silicon (a-Si) TFT technology has the treatment temperature of 300-450 ℃ in the production process, the low-temperature polysilicon TFT technology needs higher heat treatment temperature in the panel manufacturing process, a glass substrate cannot deform in multiple high-temperature treatment processes, the strain point of the glass substrate is generally required to be higher than 650 ℃ and has the heat shrinkage rate as small as possible, and meanwhile, the expansion coefficient of the glass substrate needs to be close to that of silicon, so the linear heat expansion coefficient of the glass substrate is required to be lower than 38 × 10^-7/° c; therefore, alkali-free aluminoborosilicate glasses are required to have the following properties: low densityHigh strain point, suitable coefficient of thermal expansion (less than 38 × 10)^-7/° c), high young's modulus, chemical resistance, low thermal shrinkage, absence of internal and surface defects (bubbles, waves, inclusions, etc.), and the like.

For borosilicate glass systems, boron is an important component of glass, affects batch preparation, melting and substrate physicochemical properties throughout the glass, and also has a fluxing action, and the introduction mode of boron elements in TFT glass is as follows: boric anhydride, boric acid and boric anhydride/boric acid, but no matter how boron is introduced, boron volatilization phenomenon (up to 15%) exists in the glass melting process, so that the components of the substrate glass are different from the original design values, the uniformity of the glass is damaged, even environmental pollution is caused, the consumption of raw materials is increased, a kiln furnace is corroded, the kiln age is shortened, and the operation cost of a production line is increased.

Disclosure of Invention

The invention aims to solve the problems of large boron volatilization amount, serious kiln corrosion and poor product glass uniformity in the melting process of the existing borosilicate glass system, and provides alkali-free aluminoborosilicate glass.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an alkali-free aluminoborosilicate glass is characterized by being prepared from the following raw materials in percentage by weight (calculated by oxides): 60-72% SiO₂13-18% of Al₂O₃8.5-10% of B₂O₃1-4.5% of MgO, 3-8% of CaO, 1-5% of SrO and 0.5-2% of ZrO₂1-5% of P₂O₅0.1-0.5% of SnO₂；

Wherein SiO is₂+Al₂O₃76-85%;

(MgO+CaO+SrO)/Al₂O₃0.4-0.7%;

the total content of alkaline earth metal oxide is 5-11.5%;

B₂O₃/(B₂O₃+ZrO₂+P₂O₅) 0.6-0.9%;

(ZrO₂+P₂O₅) 0.15-0.8% of (MgO + CaO + SrO).

Further, the alkali-free aluminoborosilicate glass is characterized by being prepared from the following raw materials in percentage by weight (calculated by oxides): 61.8-70.5% SiO₂13-17.5% of Al₂O₃8.5-10% of B₂O₃1 to 4.02 percent of MgO, 3.05 to 6.2 percent of CaO, 1.05 to 4.4 percent of SrO and 0.5 to 1.96 percent of ZrO₂1-4.93% of P₂O₅0.1-0.5% of SnO₂；

Wherein SiO is₂+Al₂O₃77.4-83.5%;

(MgO+CaO+SrO)/Al₂O₃0.42-0.65%;

the total content of alkaline earth metal oxide is 5.45-10.3%;

B₂O₃/(B₂O₃+ZrO₂+P₂O₅) 0.62-0.83%;

(ZrO₂+P₂O₅) 0.15-0.7% of (MgO + CaO + SrO).

Further, the alkali-free aluminoborosilicate glass has a composition with β -OH value of less than 0.5%, boron volatility of less than 11%, and coefficient of thermal expansion in the range of 50-350 ℃ of less than 39.5 × 10^-7/° C, Young's modulus higher than 78GPa, strain point higher than 690 ℃, melting temperature lower than 1662 ℃ and thermal shrinkage lower than 11.5 ppm.

Further, the alkali-free aluminoborosilicate glass has a composition having an β -OH value of 0.11 to 0.47%, a boron volatilization rate of 5.67 to 10.37%, and a thermal expansion coefficient of 33.70 to 39.5 × 10 at 50 to 350 ℃^-7The Young modulus is 78.2-84.1GPa, the strain point is 690-739 ℃, the melting temperature is lower than 1662 ℃, and the thermal shrinkage rate is 7.68-11.45 ppm.

In the glass composition of the present invention:

SiO in the glass composition₂Is a glass former, the components constituting the glass skeleton are increased by SiO₂And (3) the chemical resistance, mechanical strength and strain point are improved. If SiO₂Too much, the high-temperature viscosity of the glass is increased, which causes refractory property and aggravates the corrosion of the refractory material,SiO₂if the content is low, glass is not easy to form, the strain point is reduced, the expansion coefficient is increased, and the acid resistance and the alkali resistance are reduced; in consideration of properties such as melting temperature, glass expansion coefficient, mechanical strength, glass frit property and the like, 60-72wt% of SiO is introduced into the glass₂。

Al in the glass composition₂O₃Is intermediate oxide for improving the strength and strain point of glass structure, improving the chemical stability of glass, reducing the devitrification tendency of glass, and Al₂O₃Excessive content, difficult melting of glass, short material property, easy crystallization and Al₂O₃The content is low, the glass is easy to devitrify, the mechanical strength is low, and the forming is not facilitated, 13 to 18 weight percent of Al is introduced into the invention₂O₃。

In the glass composition B₂O₃Can produce glass independently, is a good fluxing agent, can reduce the viscosity, dielectric loss and vibration loss of the glass, improves the brittleness, toughness and light transmittance of the glass, and has [ BO ] in the glass₄]Tetrahedron and [ BO₃]Two structures of triangle, B under high temperature melting condition₂O₃Difficult to form [ BO₄]Can reduce high temperature viscosity, and B can deprive free oxygen to form [ BO ] at low temperature₄]The tendency of the invention leads the structure to be compact, improves the low-temperature viscosity of the glass, prevents the occurrence of crystallization phenomenon, and introduces 8.5 to 10 weight percent of B₂O₃。

MgO in the glass composition has the effects of reducing high-temperature viscosity and increasing low-temperature viscosity, can increase Young modulus and specific modulus of glass, and inhibits the brittleness increase of the glass, and 1-4.5wt% of MgO is introduced in the glass composition.

The alkaline earth metal oxide RO (CaO, SrO, BaO) in the glass composition can improve the strain point and Young modulus of the glass, reduce the coefficient of thermal expansion, effectively reduce the high-temperature viscosity of the glass so as to improve the meltability and the formability of the glass, and increase the occurrence probability of devitrification phase separation when the content is too much, and 5-11.5wt% of RO is introduced.

The glass composition is introduced with ZrO₂Promoting the melting of the glass and improving the quality of the glassThe Young modulus and the breaking strength of the glass are reduced, the high-temperature resistivity of the glass is reduced, the stability of the glass is promoted, the density and the thermal expansion coefficient of the glass are increased too much, and 0.5 to 2 weight percent of ZrO is introduced into the invention₂。

The glass composition is introduced with P₂O₅The invention introduces 1-5wt% of P to improve the strain point and the devitrification resistance of the glass₂O₅。

The glass composition is defined by the definition B₂O₃/(B₂O₃+ZrO₂+P₂O₅) 0.62-0.83%; (ZrO)₂+P₂O₅) 0.15-0.7 percent of (MgO + CaO + SrO), inhibits the volatilization of boron, controls the β -OH value between 0.1-0.5, improves the meltability of glass and is beneficial to industrialized production.

The composition for glass of the present invention, when used for preparing aluminosilicate glass, enables the glass to have excellent overall properties mainly due to the coordination of the components in the composition, especially SiO₂、Al₂O₃、B₂O₃、MgO、CaO、SrO、ZrO₂、P₂O₅And more particularly, the specific amounts of the components mentioned above.

The invention has the beneficial effects that:

(1) the glass disclosed by the invention has the characteristics of higher strain point, high Young modulus, high hardness, high specific modulus, proper thermal expansion coefficient, low thermal shrinkage and the like, and particularly reduces the boron volatilization rate by 5.6-10.5%, so that the phenomenon of component nonuniformity caused by boron volatilization is effectively controlled.

(2) Boron in the glass belongs to volatile light elements, and volatilization of the boron brings non-uniformity of glass components on one hand, so that a glass substrate has strip-shaped stripes and devitrification substances when serious, the boron volatilization rate is reduced, and the yield and the product quality are improved in the subsequent processing of the substrate; on the other hand, boron volatilizes in the glass production process and brings great harm to the operation of the kiln process, volatilized boron elements are easy to condense again when being cooled, the burning condition of the kiln is easy to change when the boron elements are condensed to block the burning gun at the burning gun port, the whole kiln process cannot normally operate when the boron elements are serious, the boron elements are condensed to the smoke exhaust pipeline to increase the smoke exhaust resistance, the burning pressure of the kiln is increased, and the gas burning is insufficient. The reduction of the boron volatilization rate ensures that the process operates stably, the temperature of the kiln keeps continuously controlled indexes, and the production is normally carried out.

(3) Is suitable for float forming process, and contains no As₂O₃、Sb₂O₃And the like, belongs to an environment-friendly formula, accords with the development trend of the flat panel display industry, and is suitable for large-scale industrial production; is particularly suitable for the glass substrate for the LCD/OLED display.

Detailed Description

The alkali-free aluminoborosilicate glass comprises the following specific implementation steps:

a process for preparing alkali-free aluminoborosilicate glass by the proportioning of SiO in Table 1-5₂、Al₂O₃、B₂O₃、MgO、CaO、SrO、ZrO₂、P₂O₅The composition contains Si-containing compounds, Al-containing compounds, B-containing compounds, Mg-containing compounds, Ca-containing compounds, Sr-containing compounds, Zr-containing compounds and P-containing compounds (such as carbonate, nitrate, sulfate, oxide and the like containing the elements, and the content of each component is calculated by the oxide of each element), the composition contains a clarifying agent according to different glass preparation processes, and the specific selection of the clarifying agent is not particularly limited and can be various selections commonly used in the field; under the heating condition, the SiO₂、Al₂O₃、B₂O₃、MgO、CaO、SrO、ZrO₂、P₂O₅After being mixed uniformly, the mixture is melted at high temperature (1450 and 1650 ℃), clarified and homogenized, molded and annealed (higher than 600 ℃) to obtain the alkali-free aluminoborosilicate glass substrate, and then the processing treatments such as cutting, grinding, polishing and the like are carried out.

The glass is substantially free of alkali metal oxides and substantially free of BaO.

The clarifier can be any one of calcium sulfate, strontium nitrate and calcium chloride, and can also be a composite clarifier, such as at least one of sulfate, nitrate and chloride.

It will be understood by those skilled in the art that the manner of controlling β -OH value according to the present invention includes selecting raw materials having a low water content, and adding components that reduce the water content of the glass (e.g., adding Cl, SO)₃Etc.); reducing the water content in the furnace environment; n in molten glass₂Bubbling; a small-sized smelting furnace is adopted; the flow rate of the molten glass is accelerated; the electrofusion method is well known to those skilled in the art and will not be described in detail herein.

Preferably, the glass composition of the present invention has an β -OH value of 0.11 to 0.47%, a boron volatility of 5.67 to 10.37%, and a coefficient of thermal expansion in the range of 50 to 350 ℃ of 33.70 to 39.5 × 10^-7The Young modulus is 78.2-84.1GPa, the strain point is 690-739 ℃, the melting temperature is lower than 1662 ℃, and the thermal shrinkage rate is 7.68-11.45 ppm.

The invention provides an application of the glass composition which is alkali-free aluminosilicate glass in the preparation of display devices and/or photoelectric devices, preferably in the preparation of TFT-LCD glass substrates and/or OLED glass substrates.

In the following examples and comparative examples:

the hydroxyl content in the glass was calculated using fourier transform infrared spectrometer analysis in%.

The hydroxyl content in the glass was calculated using fourier transform infrared spectrometer analysis in%.

The boron volatilization rate: the boron content is obtained by comparing the boron content with the boron content in the glass raw material, and the unit is%.

The coefficient of thermal expansion of the glass at 50-350 ℃ was measured in 10 units using a horizontal dilatometer with reference to ASTME-228^-7/℃。

Vickers Hardness (HV) was determined using an automatic digital turret display micro vickers hardness tester, referred to GB/T4340.2-2012.

The Young's modulus of the glass is measured in GPa by using a mechanical testing machine according to ASTM C-623, and the specific modulus is calculated from the ratio of the Young's modulus to the density and is measured in GPa/(g × cm)^-3)。

The annealing and strain points of the glasses were measured in degrees centigrade using a three-point tester with reference to astm c-336 and astm c-338.

The glass high temperature visco-temperature curve was determined using a rotary high temperature viscometer with reference to astm c-965, where the temperature at 200P viscosity corresponds to the melting temperature in c.

The heat shrinkage was calculated using the difference. A glass substrate without any defects, the initial length of which is marked as L0, after being subjected to heat treatment under certain conditions (for example, the heat treatment process conditions of the invention are that the glass is heated to 600 ℃ from room temperature at a heating rate of 10 ℃/min and is kept for 10min, and then the glass is cooled to room temperature at a cooling rate of 10 ℃/min), the length of the substrate is shrunk by a certain amount, the length of the substrate is measured again, the length is marked as Lt, and the heat shrinkage Yt is expressed as:

specific examples and comparative examples are given below, in weight percentages, of the components of the formulation, see tables 1, 2, 3, 4, 5:

table 1.

The components by weight percent	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7	Example 8
									SiO2	60.15	60.26	60.39	60.53	61.45	61.57	61.64	61.89
Al2O3	17.59	16.50	17.01	16.42	16.56	16.22	18.00	16.44
									B2O3	8.94	9.81	9.92	8.53	8.81	9.13	8.50	8.73
MgO	1.86	2.53	1.26	2.57	2.78	2.04	2.48	3.47
									CaO	4.11	3.38	6.43	5.56	6.19	5.35	3.56	3.25
SrO	1.42	1.53	2.37	3.08	1.19	2.30	2.32	4.32
									ZrO2	0.50	0.80	1.00	1.71	0.71	1.51	1.36	0.79
P2O5	4.93	4.89	1.12	1.10	2.20	1.75	1.99	1.01
									SnO2	0.50	0.30	0.50	0.50	0.11	0.13	0.15	0.10
SiO2+Al2O3	77.74	76.76	77.40	76.95	78.01	77.79	79.64	78.33
									(MgO+CaO+SrO)/Al2O3	0.42	0.45	0.59	0.68	0.61	0.60	0.46	0.67
Total amount of alkaline earth metals	7.39	7.44	10.06	11.21	10.16	9.69	8.36	11.04
									B2O3/(B2O3+ZrO2+P2O5)	0.62	0.63	0.82	0.75	0.75	0.74	0.72	0.83
(ZrO2+P2O5)/(MgO+CaO+SrO)	0.73	0.76	0.21	0.25	0.29	0.34	0.40	0.16
									β-OH	0.36	0.29	0.19	0.24	0.3	0.39	0.38	0.4
Boron volatility%	9.56	10.33	10.17	9.23	8.42	9.71	10.35	10.06
									Thermal expansion coefficient (50-350 deg.C) 10-7/℃	39.5	38.1	38.8	35.9	36.6	35.7	39.4	36.8
Young's modulus GPa	78.90	80.6	79.8	81.2	80.4	79.9	81.8	78.3
									Vickers hardness Hv	679.7	677.1	676.3	673.8	674.7	679.4	680.8	678.3
Specific modulus GPa/g × cm-3	30.46	31.24	30.69	31.21	32.83	31.49	32.04	31.63
									Strain point of DEG C	711.00	706	690	712	720	704	693	726
Melting temperature T2.3℃	1601.00	1612	1606	1613	1608	1632	1613	1622
									Heat shrinkage (600 ℃ C., 10 min) ppm	10.84	11.03	9.05	10.74	11.37	7.68	11.29	10.48

Table 2.

Componentswt%	Example 9	Example 10	Example 11	Example 12	Example 13	Example 14	Example 15	Example 16
									SiO2	62.35	62.51	62.73	62.80	63.24	63.73	63.81	64.17
Al2O3	16.11	16.03	15.30	15.19	15.52	14.32	14.52	14.05
									B2O3	9.23	8.62	10.00	9.31	8.72	8.81	9.01	8.55
MgO	4.02	2.85	4.01	3.25	3.13	1.65	2.56	1.95
									CaO	3.66	4.69	5.14	4.17	3.25	4.16	5.03	4.14
SrO	2.61	1.83	1.15	1.14	1.19	3.55	2.15	2.08
									ZrO2	0.58	1.21	0.55	1.10	0.55	1.59	1.31	1.21
P2O5	1.29	2.14	1.01	2.89	4.27	2.07	1.46	3.74
									SnO2	0.15	0.12	0.11	0.15	0.13	0.12	0.15	0.11
SiO2+Al2O3	78.46	78.54	78.03	77.99	78.76	78.05	78.33	78.22
									(MgO+CaO+SrO)/Al2O3	0.64	0.58	0.67	0.56	0.49	0.65	0.67	0.58
Total amount of alkaline earth metals	10.29	9.37	10.30	8.56	7.57	9.36	9.74	8.17
									B2O3/(B2O3+ZrO2+P2O5)	0.83	0.72	0.87	0.70	0.64	0.71	0.76	0.63
(ZrO2+P2O5)/(MgO+CaO+SrO)	0.18	0.36	0.15	0.47	0.64	0.39	0.28	0.61
									β-OH	0.37	0.34	0.32	0.28	0.31	0.35	0.24	0.18
Boron volatility%	9.52	10.37	9.19	8.62	7.06	8.87	9.45	10.23
									Thermal expansion coefficient (50-350 deg.C) 10-7/℃	37.1	38.5	36.4	39.3	37.9	35.2	34.6	36.9
Young's modulus GPa	80.6	78.2	79.4	81.7	79.6	81.2	79.7	80.3
									Vickers hardness Hv	677.4	673.9	678.5	668.6	680.3	679.4	677.1	676.9
Specific modulus GPa/g × cm-3	30.7	31.34	32.06	30.65	31.27	30.25	30.94	31.83
									Strain point of DEG C	706	694	725	718	724	708	713	725
Melting temperature T2.3℃	1634	1609	1614	1621	1626	1618	1605	1622
									Heat shrinkage (600 ℃ C., 10 min) ppm	10.83	8.75	10.71	8.35	9.56	11.25	10.76	8.89

Table 3.

The components by weight percent	Example 17	Example 18	Example 19	Example 20	Example 21	Example 22	Example 23	Example 24
									SiO2	64.55	65.39	65.61	65.82	66.41	66.83	67.17	67.42
Al2O3	14.26	14.61	14.14	14.09	13.86	13.29	13.02	13.15
									B2O3	8.91	9.15	8.64	9.26	8.55	8.75	9.03	9.59
MgO	2.08	1.99	2.15	1.64	1.95	2.17	3.05	1.15
									CaO	3.65	4.17	3.55	4.86	4.91	4.05	4.22	3.64
SrO	2.87	2.06	2.18	1.09	2.37	1.96	1.25	1.47
									ZrO2	1.96	1.32	1.35	0.85	0.75	1.63	0.79	1.95
P2O5	1.60	1.21	2.23	2.27	1.05	1.20	1.36	1.48
									SnO2	0.12	0.10	0.15	0.12	0.15	0.12	0.11	0.15
SiO2+Al2O3	78.81	80.00	79.75	79.91	80.27	80.12	80.19	80.57
									(MgO+CaO+SrO)/Al2O3	0.60	0.56	0.56	0.54	0.67	0.62	0.65	0.48
Total amount of alkaline earth metals	8.60	8.22	7.88	7.59	9.23	8.18	8.52	6.26
									B2O3/(B2O3+ZrO2+P2O5)	0.71	0.78	0.71	0.75	0.83	0.76	0.81	0.74
(ZrO2+P2O5)/(MgO+CaO+SrO)	0.41	0.31	0.45	0.41	0.20	0.35	0.25	0.55
									β-OH	0.21	0.26	0.22	0.17	0.11	0.2	0.14	0.16
Boron volatility%	6.92	8.35	10.24	10.22	9.95	5.67	6.52	9.57
									Thermal expansion coefficient (50-350 deg.C) 10-7/℃	35.6	34.7	35.1	36.3	35.7	34.4	33.7	35.6
Young's modulus GPa	81.6	80.7	79.2	81.5	84.1	81.3	82.4	80.9
									Vickers hardness Hv	668.3	673.8	669.4	678.4	679.1	682.2	681.6	678.6
Specific modulus GPa/g × cm-3	32.31	30.97	31.62	30.76	33.29	31.62	32.97	31.86
									Strain point of DEG C	719	716	720	709	721	719	724	722
Melting temperature T2.3℃	1618	1628	1632	1638	1619	1633	1621	1636
									Heat shrinkage (600 ℃ C., 10 min) ppm	9.42	10.59	7.83	8.92	9.21	10.34	9.11	11.45

Table 4.

The components by weight percent	Example 25	Example 26	Example 27	Example 28	Example 29	Example 30	Example 31	Example 32
									SiO2	67.78	68.14	68.63	68.85	69.31	69.79	70.33	70.71
Al2O3	13.05	14.21	13.04	13.17	13.35	13.07	13.01	13.00
									B2O3	8.83	8.62	8.57	8.74	8.74	8.85	8.55	8.67
MgO	1.42	1.03	2.25	1.19	2.12	1.92	1.38	1.16
									CaO	3.11	3.28	3.08	3.13	3.35	3.34	3.45	3.25
SrO	3.06	1.87	1.72	1.38	1.16	1.02	1.17	1.04
									ZrO2	0.97	0.95	0.73	1.33	0.63	0.55	0.75	1.01
P2O5	1.64	1.79	1.86	2.06	1.21	1.31	1.21	1.02
									SnO2	0.14	0.11	0.12	0.15	0.13	0.15	0.15	0.14
SiO2+Al2O3	80.83	82.35	81.67	82.02	82.66	82.86	83.34	83.71
									(MgO+CaO+SrO)/Al2O3	0.58	0.43	0.54	0.43	0.50	0.48	0.46	0.42
Total amount of alkaline earth metals	7.59	6.18	7.05	5.70	6.63	6.28	6.00	5.45
									B2O3/(B2O3+ZrO2+P2O5)	0.77	0.76	0.77	0.72	0.83	0.83	0.81	0.81
(ZrO2+P2O5)/(MgO+CaO+SrO)	0.34	0.44	0.37	0.59	0.28	0.30	0.33	0.37
									β-OH	0.2	0.25	0.19	0.22	0.24	0.23	0.33	0.24
Boron volatility%	8.63	7.39	10.36	7.18	10.06	7.25	9.03	10.24
									Thermal expansion coefficient (50-350 deg.C) 10-7/℃	34.2	36.6	35.5	36.3	34.8	37.1	37.4	36.2
Young's modulus GPa	81.5	79.6	80.4	81.7	80.3	82.6	79.8	80.9
									Vickers hardness Hv	680.5	678.9	679.5	680.8	669.4	679.3	680.1	677.4
Specific modulus GPa/g × cm-3	30.4	32.64	31.32	30.24	32.69	31.93	31.44	32.36
									Strain point of DEG C	714	727	731	739	733	736	728	730
Melting temperature T2.3℃	1628	1634	1648	1652	1643	1660	1639	1651
									Heat shrinkage (600 ℃ C., 10 min) ppm	9.97	10.63	9.03	11.31	9.66	10.23	11.02	10.76

Table 5.

The components by weight percent	Example 33	Example 34	Example 35	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
								SiO2	71.23	71.66	71.90	59.03	73.84	66.42	66.5
Al2O3	13.09	13.00	13.00	19.23	12.42	13.51	13.45
								B2O3	8.65	8.51	8.50	11.64	8.01	8.37	8.51
MgO	1.00	1.09	1.00	6.17	0.56	2.01	1.95
								CaO	3.03	3.05	3.00	2.07	1.83	4.98	5.05
SrO	1.01	1.02	1.00	0.50	0.72	2.85	2.8
								ZrO2	0.62	0.51	0.50	0.45	0.47		1.59
P2O5	1.24	1.06	1.00	0.76	2.00	1.71
								SnO2	0.13	0.10	0.10	0.15	0.15	0.15	0.15
SiO2+Al2O3	84.32	84.66	84.90	78.26	86.26	79.93	79.95
								(MgO+CaO+SrO)/Al2O3	0.39	0.40	0.38	0.45	0.25	0.73	0.73
Total amount of alkaline earth metals	5.04	5.16	5.00	8.74	3.11	9.84	9.80
								B2O3/(B2O3+ZrO2+P2O5)	0.82	0.84	0.85	0.91	0.76	0.83	0.84
(ZrO2+P2O5)/(MgO+CaO+SrO)	0.37	0.30	0.30	0.14	0.79	0.17	0.16
								β-OH	0.34	0.47	0.41	0.61	0.53	0.78	0.86
Boron volatility%	10.31	9.86	10.11	14.8	13.5	12.76	12.31
								Thermal expansion coefficient (50-350 deg.C) 10-7/℃	35.9	37.3	38.1	38.1	36.5	36.3	35.8
Young's modulus GPa	81.7	80.3	82.1	73.3	76.9	77.6	75.4
								Vickers hardness Hv	679.5	671.7	676.6	642.4	659.2	650.7	639.6
Specific modulus GPa/g × cm-3	30.04	31.72	30.95	27.93	32.67	28.14	29.92
								Strain point of DEG C	735	726	729	658	684	662	675
Melting temperature T2.3℃	1649	1658	1662	1603	1672	1621	1618
								Heat shrinkage (600 ℃ C., 10 min) ppm	8.48	11.08	9.73	20.16	14.28	15.04	9.52