CN109678341B

CN109678341B - Alkali-free glass composition, alkali-free glass and application

Info

Publication number: CN109678341B
Application number: CN201811512297.4A
Authority: CN
Inventors: 张广涛; 李青; 郑权; 王丽红; 闫冬成; 安利营; 王俊峰; 田鹏
Original assignee: Dongxu Optoelectronic Technology Co Ltd
Current assignee: Dongxu Optoelectronic Technology Co Ltd
Priority date: 2018-12-11
Filing date: 2018-12-11
Publication date: 2022-03-25
Anticipated expiration: 2038-12-11
Also published as: CN109678341A

Abstract

The invention relates to the field of glass, and discloses an alkali-free glass composition, alkali-free glass and a preparation method thereof. The alkali-free glass composition comprises: the glass composition contains 58-64 wt% SiO based on the total weight of the alkali-free glass composition₂16-19 wt% of Al₂O₃7-13 wt% of B₂O₃+P₂O₅0.5-3.5 wt% of MgO, 4-8 wt% of CaO, 0.1-4 wt% of SrO, 0-2.5 wt% of BaO, 0-4 wt% of ZnO, less than 0.05 wt% of R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of O content. The glass prepared by the composition has higher mechanical strength, smaller density, higher chemical resistance (namely high chemical stability) and low thermal expansion coefficient (lower than 38 multiplied by 10)^‑7/° c), higher strain point temperature and the like, can be used for preparing display devices and/or solar cells, and has good application prospect.

Description

Alkali-free glass composition, alkali-free glass and application

Technical Field

The invention relates to the field of glass, in particular to an alkali-free glass composition, alkali-free glass and application.

Background

Liquid crystal display technology has become the most important key technology for image transmission and reproduction in modern times. The display principle of liquid crystal display is that liquid crystal is placed between two pieces of conductive glass, and driven by electric field between two electrodes to produce electric field effect of twisted nematic liquid crystal molecules, so as to control light source transmission or shielding function, and produce light and shade between power supply switch to display image, if a colour filter is added, it can display colour image. The TFT liquid crystal display mode has a pixel response speed 600 times faster than that of the old LCD screen. The advanced silicon electrode is added to greatly increase the pixel response speed of the liquid crystal screen and reduce the delay phenomenon of the picture. The glass substrate is subjected to higher technical requirements, the geometric dimension of the processed substrate is not influenced by heat conditions, namely the thermal expansion coefficient of the glass substrate is small, and the optimal thermal expansion coefficient is 28 multiplied by 10 according to the comprehensive consideration of the production stress in the glass substrate manufacturing^-7Around/° c.

A glass substrate for TFT-LCD is required to form a transparent conductive film, an insulating film, a semiconductor (polysilicon, amorphous silicon, etc.) film and a metal film on the glass surface of an underlying substrate by sputtering, Chemical Vapor Deposition (CVD) or the like, and then to form various circuits and patterns by Photo-etching (Photo-etching) technique if the glass contains an alkali metal oxide (Na-oxide)₂O，K₂O，Li₂O), alkali metal ions diffusing into the deposited semiconductor material during heat treatment, impairing the semiconductor film characteristics, and therefore the glass should be free of alkali metal oxides, and alkali-free glasses, preferably SiO, must be used₂、Al₂O₃、B₂O₃And alkali-free boroaluminosilicate glasses containing an alkaline earth metal oxide RO (RO ═ Mg, Ca, Sr, Ba) as a main component.

At present, with the rapid popularization of portable electronic equipment (such as notebook computers, smart phones and PDAs), higher requirements are put on the light weight of accessories. Therefore, higher requirements are put on the components of the glass substrate so as to ensure the glass substrate to meet the requirements of modern liquid crystal displays. The glass substrate must have the following characteristics: contains less than 1000ppm of alkali metal oxide; has chemical resistance; the thermal expansion coefficient is close to the silicon of the thin film transistor; the strain point of the glass is improved to reduce the heat shrinkage; has small density, and is convenient for carrying and holding.

In addition to being lightweight, glass substrates for portable electronic devices also need to meet the demands of people to perform and enjoy higher levels of business and entertainment activities at all times. Such demands are increasing the performance requirements of displays, especially the picture quality of mobile intelligent devices and the outdoor visual performance requirements are also increasing. Under the guidance of such development trend, the display panel is developing towards light, thin and ultra-high definition display, and on one hand, the glass substrate is required to have smaller density; on the other hand, the panel process is developing to a higher processing temperature; meanwhile, the thickness of the single glass sheet is treated by the process, and the thickness of the single glass sheet reaches 0.25mm, 0.2mm, 0.1mm and 0.05mm or even thinner.

The method for thinning glass mainly comprises chemical thinning, specifically, a hydrofluoric acid or hydrofluoric acid buffer solution is used for corroding a glass substrate, and the thinning principle is as follows:

the main chemical reactions are as follows: 4HF + SiO₂＝SiF₄+2H₂O；

Secondary chemical reaction: RO +2H⁺＝R²⁺+H₂O (R represents an alkaline earth metal or the like).

The chemical thinning process and the surface quality of the thinned glass substrate have a certain relation with the composition of basic glass, and the existing TFT-LCD substrate glass frequently has poor defects such as pits, concave-convex points and the like in the chemical thinning process, so that the production cost is increased. The glass with high chemical stability has better surface quality after being thinned, so that the development of the TFT-LCD substrate glass with high chemical stability can reduce the production cost of secondary polishing and the like, improve the product quality and the yield, and has great benefits for large-scale industrial production. Too slow hydrofluoric acid or hydrofluoric acid buffer corrosion rate may reduce the production efficiency of the thinning plant.

According to the technical standards of liquid crystal displays, a glass substrate for a TFT-LCD must have the following basic physical properties:

1. glass substrateMust be sufficiently low as not higher than 38X 10^-7/℃；

2. The strain point temperature of the glass substrate is higher than 640 ℃;

3. the density is less than 2.6g/cm³And the lighter the better.

However, with the progress of liquid crystal display technology, curved display and advanced generation panels have new requirements on the performance of glass substrates, for example, the glass substrates can bear the requirement of smaller curvature radius without cracking when being bent, and the large-size substrates have the smallest sagging amount during the transmission process. This requires that the glass substrate have improved mechanical properties such as flexural strength, Young's modulus, specific modulus, and the like. In general, the improvement (enhancement) of mechanical properties tends to bring about undesirable changes in the viscosity in the medium-temperature region (strain point, annealing point, vicinity of softening point) and the viscosity in the high-temperature region (molding temperature, melting temperature, etc.). For example, in a practical alkali-free liquid crystal glass composition, Al₂O₃The addition of oxides such as MgO, SrO, BaO and the like improves the Young's modulus, but all have the disadvantage of deteriorating the physical and chemical properties in other aspects, for example, improving Al₂O₃Content, which results in a large increase in liquidus temperature; the increased MgO content leads to increased phase splitting tendency, greatly increased liquidus temperature and greatly reduced low-temperature viscosity; increasing the SrO content and/or BaO content results in increased high temperature viscosity and greatly increased density of the glass, which is not favorable for increasing the specific modulus.

CN105392743A discloses an alkali-free glass with high Young's modulus and high specific elastic modulus, wherein the Young's modulus is more than 94.5GPa, and the specific elastic modulus is 34.5 GPa/(g/cm)³) Above, but with too high an expansion coefficient, the average thermal expansion coefficient between 50 and 350 ℃ is all more than 38 multiplied by 10^-7/° c, the technical requirements of TFT liquid crystal display cannot be met;

CN104211300A discloses an alkali-free glass formulation with high specific modulus, the elastic modulus is higher than 82GPa, and the specific modulus is higher than 33 GPa/(g/cm)³) Meanwhile, the high-viscosity high-temperature-zone-viscosity high-temperature-resistant steel has a high medium-temperature-zone viscosity, and the strain point is higher than 720 ℃. In order to achieve the above object, this application uses Al in a large amount in composition₂O₃And less B₂O₃In order to provide both mechanical strength and thermal stability. However, this composition characteristic causes a significant decrease in chemical resistance, particularly hydrofluoric acid corrosion resistance, which is not favorable for the current demand for thinner and lighter substrates.

Therefore, there is a need for a glass that combines improved mechanical properties with other properties to meet the requirements of TFT liquid crystal display technology.

Disclosure of Invention

The invention aims to overcome the problem that the mechanical property of the glass is improved to damage other properties (such as heat stability and chemical corrosion resistance) so that the glass cannot meet the technical requirements of TFT liquid crystal display in the prior art, and provides an alkali-free glass composition, alkali-free glass and application.

In order to achieve the above object, a first aspect of the present invention provides an alkali-free glass composition comprising: the glass composition contains 58-64 wt% SiO based on the total weight of the alkali-free glass composition₂16-19 wt% of Al₂O₃7-13 wt% of B₂O₃+P₂O₅0.5-3.5 wt% of MgO, 4-8 wt% of CaO, 0.1-4 wt% of SrO, 0-2.5 wt% of BaO, 0-4 wt% of ZnO, less than 0.05 wt% of R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of O content.

In a second aspect, the present invention provides a glass made from the glass composition of the present invention.

In a third aspect, the present invention provides a method of making glass from the glass composition of the first aspect of the invention, the method comprising: the glass composition of the first aspect of the present invention is subjected to melting, forming, annealing, and machining.

The alkali-free glass prepared from the glass composition has high mechanical strength, appropriate chemical resistance and excellent heat stability, and particularly has the following performance standards:

a. maximum stress value sigma of bending test_maxNot less than 80 MPa; and

b. maximum strain epsilon of bending test_max≥1500×10^-6。

In addition, other physical properties of the alkali-free glass can be stably achieved:

(1) the density is less than or equal to 2.49g/cm³；

(2) A coefficient of thermal expansion in the range of 50-350 ℃ of less than 38 x 10^-7/℃；

(3) Young's modulus is greater than or equal to 72GPa, specific modulus is greater than or equal to 30GPa (g/cm)³)；

(4) Strain point T_stIs 650-730 ℃;

(5) liquidus temperature T_L≤1200℃；

(6) A temperature T corresponding to a viscosity of 200 poise₂₀₀≤1630℃；

(7) The corrosion rate of hydrofluoric acid is 4mg/cm²-6.5mg/cm²；

(8) The transmittance at the wavelength of 308nm is more than or equal to 50 percent;

(9) the surface tension is less than or equal to 370mN/m at 1200 ℃;

(10) vickers hardness greater than or equal to 580kgf/cm²；

(11) The refractive index nD is less than or equal to 1.53.

Preferably, the characteristics of the alkali-free glass can be stably achieved by:

(1) maximum stress value sigma of bending test_maxNot less than 100 MPa; and

(2) maximum strain epsilon of bending test_max≥1600×10^-6；

(3) The density is less than or equal to 2.42g/cm³；

(4) A coefficient of thermal expansion in the range of 50-350 ℃ of less than 36X 10^-7/℃；

(5) Young's modulus is greater than or equal to 73GPa, specific modulus is greater than or equal to 30.5GPa (g/cm)³)；

(6) Strain point T_stIs 680-700 ℃;

(7) liquidus temperature T_L≤1130℃；

(8) A temperature T corresponding to a viscosity of 200 poise₂₀₀≤1627℃；

(9) The corrosion rate of hydrofluoric acid is 4.5mg/cm²-5.2mg/cm²；

(10) The transmittance at the wavelength of 308nm is more than or equal to 70 percent;

(11) surface tension of less than or equal to 360mN/m at 1200 DEG C

(12) Vickers hardness is more than or equal to 620kgf/cm²；

(13) The refractive index nD is less than or equal to 1.52.

In a fourth aspect, the invention provides the use of a glass according to the second aspect of the invention in a display device and/or a solar cell.

The glass prepared by the composition has higher mechanical strength (namely high maximum stress value and maximum strain amount of a bending test), higher chemical resistance (namely high chemical stability), and low thermal expansion coefficient (lower than 38 multiplied by 10)^-7/° c), higher strain point temperature, and the like. The glass can be used for preparing display devices and/or solar cells, and is particularly suitable for preparing substrate glass substrate materials and/or glass film layer materials for screen surface protection of flat panel display products, substrate glass substrate materials and/or surface packaging glass materials and/or glass film layer materials for screen surface protection of flexible display products, substrate glass substrate materials of flexible solar cells, safety glass, bulletproof glass, intelligent automobile glass, intelligent traffic display screens, intelligent windows and intelligent card tickets and other application fields requiring glass materials with high thermal stability and mechanical stability.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In a first aspect, the present invention provides an alkali-free glass composition comprising: the glass composition contains 58-64 wt% SiO based on the total weight of the alkali-free glass composition₂16-19 wt% of Al₂O₃、7-13wt% of B₂O₃+P₂O₅0.5-3.5 wt% of MgO, 4-8 wt% of CaO, 0.1-4 wt% of SrO, 0-2.5 wt% of BaO, 0-4 wt% of ZnO, less than 0.05 wt% of R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of O content.

According to the present invention, the glass composition comprises, based on the total weight of the alkali-free glass composition: 58-64 wt% SiO₂E.g. SiO₂The amount of (b) can be any value within the range of 58 wt%, 58.4 wt%, 58.5 wt%, 58.9 wt%, 59.5 wt%, 59.7 wt%, 59.8 wt%, 60 wt%, 61.4 wt%, 61.7 wt%, 61.8 wt%, 61.9 wt%, 62 wt%, 62.1 wt%, 62.2 wt%, 62.3 wt%, 62.4 wt%, 62.5 wt%, 62.6 wt%, 62.7 wt%, 62.8 wt%, 62.9 wt%, 63 wt%, 63.3 wt%, 63.6 wt%, 63.7 wt%, 63.8 wt%, 63.9 wt%, 64 wt%, and any two of these values;

16-19 wt% Al₂O₃For example Al₂O₃The amount of (b) may be 16 wt%, 16.3 wt%, 16.8 wt%, 17.1 wt%, 17.2 wt%, 17.3 wt%, 17.4 wt%, 17.5 wt%, 17.6 wt%, 17.7 wt%, 17.8 wt%, 17.9 wt%, 18 wt%, 18.1 wt%, 18.3 wt%, 18.5 wt%, 18.8 wt%, 18.9 wt%, 19 wt%, and any value in the range of any two of these points;

7-13 wt% of B₂O₃+P₂O₅E.g. B₂O₃、P₂O₅The sum of (b) may be 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, and any value in the range of any two of these points;

0.5 to 3.5 wt% of MgO, for example the MgO content can be 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.1 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.1 wt%, 3.3 wt%, 3.5 wt%, and any value in the range of any two of these;

4-8 wt% CaO, for example, the CaO can be present in an amount of 4.1 wt%, 4.4 wt%, 4.8 wt%, 5 wt%, 5.2 wt%, 5.3 wt%, 5.4 wt%, 5.5 wt%, 5.6 wt%, 5.7 wt%, 5.8 wt%, 5.9 wt%, 6 wt%, 6.1 wt%, 6.2 wt%, 6.3 wt%, 6.4 wt%, 6.6 wt%, 6.8 wt%, 7.1 wt%, 7.2 wt%, 7.3 wt%, 7.5 wt%, 7.7 wt%, 8 wt%, and any value in the range of any two of these points;

0.1-4 wt% SrO, for example the SrO content can be 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, and any two of these ranges;

0 to 2.5 wt% of BaO, for example, the content of BaO may be 0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, and any value in the range of any two of these points;

0 to 4 wt% of ZnO, for example, the content of ZnO may be 0 wt%, 0.1 wt%, 0.2 wt%, 0.26 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%, 3.3 wt%, 3.7 wt%, 4 wt%, and any value in the range of any two of these points.

In the present invention, the alkali-free glass composition is understood to mean that no additional alkali metal component is required to be added to the composition, and the alkali metal component may be added in the form of any simple substance or compound containing an alkali metal element. The alkali metal includes Li, Na and/or K.

In the alkali-free glass composition of the present invention, SiO₂Is a glass former, if SiO₂The content of (A) is too low, which is not beneficial to the enhancement of chemical resistance and corrosion resistance, and can cause too high expansion coefficient, thus leading the glass to be easy to devitrify; if SiO₂The content of (A) increases, and SiO contributes to weight reduction of the glass, reduction of the thermal expansion coefficient, increase of the strain point and increase of the chemical resistance, but₂Too high a content of (b) can cause the high-temperature viscosity of the prepared alkali-free glass to be increased, namely the melting temperature to be increased, which is not beneficial to melting, and a common kiln can not meet the requirement of batch melting of materials by the conventional high-capacity melting technology. Thus, preferably, SiO₂In an amount of 58 to 64% by weight, which is advantageous in further compromising the resistance to chemicals, mechanical strength and high temperature viscosity of the resulting alkali-free glass.

In the alkali-free glass composition of the present invention, Al is used₂O₃When the content of (A) is too low, the heat resistance of the glass is difficult to improve, and the glass is easy to be corroded by external moisture and chemical reagents; when Al is present₂O₃When the content of (A) is increased, it contributes to an increase in the strain point and mechanical strength of the glass, but Al₂O₃Too high a content of (b) is liable to cause devitrification, and the glass is difficult to melt. Preferably, Al is based on the total weight of the alkali-free glass composition₂O₃Is in the range of 17 to 18% by weight, which is advantageous in further optimizing the heat resistance, chemical resistance and mechanical strength of the resulting alkali-free glass and improving the devitrification performance.

In the alkali-free glass composition of the present invention, B₂O₃、P₂O₅As a matrix constituting the glass, glasses can be formed separately, and their addition enhances the chemical stability and mechanical properties of the glass, while B₂O₃、P₂O₅The glass melting agent is also a good fluxing agent, can reduce high-temperature viscosity under a high-temperature condition, can greatly reduce the glass melting temperature, and is also beneficial to the vitrification process; the B has the tendency of capturing free oxygen at low temperature, so that the structure tends to be compact, and the low temperature of the glass is improvedThe temperature is difficult, and the phenomenon of crystallization is prevented. But too much B₂O₃The strain point of the glass can be greatly reduced. Preferably, B is based on the total weight of the alkali-free glass composition₂O₃And P₂O₅The sum of the weight contents is 7wt percent and less than B₂O₃+P₂O₅Less than or equal to 13wt percent; further preferably, 8.8 wt.% B ≦ B₂O₃+P₂O₅≤11wt％。

In the alkali-free glass composition, a proper amount of ZnO is added, so that the crystallization temperature is reduced, the crystallization is further inhibited, the high-temperature viscosity of the glass can be reduced, bubbles can be eliminated, and the alkali-free glass composition has the effects of improving the strength, hardness and chemical resistance of the glass and reducing the thermal expansion coefficient of the glass below a softening point. Theoretically, ZnO is generally introduced as a network exosome in alkali-free glass and then at high temperature as [ ZnO ]₄]Exists in the form of [ ZnO ]₆]The glass structure is more loose, and compared with the glass without ZnO under the same high-temperature state, the glass containing ZnO has smaller viscosity and larger atom movement speed, cannot form crystal nucleus, needs to further reduce the temperature, is beneficial to the formation of the crystal nucleus, and thus reduces the crystallization upper limit temperature of the glass. And the too much ZnO content can greatly reduce the strain point of the glass, which is not beneficial to improving the thermal stability of the glass substrate.

In the alkali-free glass composition of the present invention, MgO, CaO, SrO and BaO are alkaline earth metal oxides, and the addition of these oxides can effectively reduce the high-temperature viscosity of the glass, thereby improving the melting property and the formability of the glass and increasing the strain point of the glass. In addition, MgO and BaO have the characteristic of improving the chemical stability and the mechanical stability of the alkali-free glass. However, when the content of the alkaline earth metal oxide is too large, the density of the alkali-free glass increases, and the incidence of cracking, devitrification, and phase separation increases.

In a preferred embodiment, the alkali-free glass composition contains 61 to 63 wt.% SiO₂17-18 wt% of Al₂O₃8.8-11 wt% of B₂O₃+P₂O₅1.1-2.7 wt% of MgO, 5.4-7.7 wt% of CaO, 1.6-3.6 wt% ofSrO, 0 wt% BaO, 0 wt% ZnO, less than 0.05 wt% R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of O content.

In the alkali-free glass composition of the present invention, it is further preferred that SiO is present in an amount based on the total weight of the alkali-free glass composition₂And Al₂O₃The sum of the contents Q satisfies Q>75 wt%; further preferably, 75 wt%<Q is less than 82 wt%; still more preferably, 78 wt% < Q < 81 wt% can maximize chemical resistance, corrosion resistance, heat resistance, workability and mechanical strength of the resulting alkali-free glass while reducing the probability of occurrence of devitrification.

In the alkali-free glass composition of the present invention, though B₂O₃、P₂O₅Are good fluxing agents, so that the raw materials are easier to melt. But B₂O₃/(B₂O₃+P₂O₅) Too low a weight percentage, for example as low as 0.1 or 0.01, will raise the liquidus temperature to some extent and also impair chemical resistance. Preferably, B₂O₃、(B₂O₃+P₂O₅) In a weight ratio of B₂O₃/(B₂O₃+P₂O₅) 0.1, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, and any value in the range of any two of these values; even more preferably, 0.8 < B₂O₃/(B₂O₃+P₂O₅)≤1。

In the composition of the present invention, alkaline earth metal oxides such as MgO, CaO, SrO, BaO are effective in reducing the high temperature viscosity of the glass, but R' O/(B)₂O₃+P₂O₅) Too high or too low a weight ratio of (A) is adversely affected, wherein R' is the sum of the contents of MgO, CaO, SrO, BaO and ZnO. When R' O/(B)₂O₃+P₂O₅) At lower levels, e.g., less than 0.5, the thermal stability of the glass is significantly reduced (where a strain point temperature T is used)_stCharacterization glassThermal stability of the glass, T_stThe higher the thermal stability of the glass), while the liquidus temperature will increase; when R' O/(B)₂O₃+P₂O₅) Higher values, for example higher than 1.9, also increase the liquidus temperature of the glass, accompanied by an increase in the thermal expansion coefficient. Thus, preferably, 0.5 < R' O/(B)₂O₃+P₂O₅) < 1.9, for example, it may be any one of 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8 and a range consisting of any two of the above values; further preferably 0.9 < R' O/(B)₂O₃+P₂O₅) < 1.3, more preferably 1.0 < R' O/(B)₂O₃+P₂O₅) < 1.2, more preferably R' O/(B)₂O₃+P₂O₅)＝1.1。

In the alkali-free glass composition of the present invention, the weight ratio of MgO and CaO also affects the liquidus temperature of the raw materials of the glass composition, for example, when the ratio of MgO/CaO is too high, the liquidus temperature of the raw materials of the glass composition is also significantly increased, which is not favorable for industrial production of glass. Therefore, the ratio of the contents of MgO and CaO, 0.1 < MgO/CaO < 0.9, may be, for example, any value in the range of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and any two of these values, and further preferably 0.15 < MgO/CaO < 0.5.

In the alkali-free glass composition of the present invention, the weight ratio of SrO to CaO also affects the liquidus temperature of the glass composition raw materials, for example, when the SrO/CaO ratio is too high, the liquidus temperature of the glass composition raw materials is also significantly increased, which is not favorable for industrial production of glass. Thus, the SrO, CaO content ratio SrO/CaO is preferably > 0.01, and may be, for example, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.8, or any value within a range defined by any two of these points; preferably 0.2 < SrO/CaO < 0.6, more preferably 0.3 < SrO/CaO < 0.45.

According to the invention, the content of BaO in the alkali-free glass composition is less than 2 wt% based on the total weight of the alkali-free glass composition; preferably, the content of BaO is less than 1.5 wt%; further preferably, the content of BaO is less than 1 wt%; further preferably, the content of BaO is less than 0.005 wt%, and still further preferably, BaO is not contained.

According to the invention, in the alkali-free glass composition, the content of ZnO is less than 2 wt% based on the total weight of the alkali-free glass composition; preferably, the content of ZnO is less than 1.2 wt%; further preferably, the content of ZnO is less than 0.8 wt%; further preferably, the content of ZnO is less than 0.005 wt%; even more preferably, no ZnO is present.

In accordance with the present invention, the alkali-free glass composition further comprises a chemical fining agent in an amount of no greater than 1 wt%, based on the total weight of the alkali-free glass composition. The chemical fining agent may be selected according to the prior art, for example, the chemical fining agent may be a tin-containing compound, such as tin oxide.

In a second aspect, the present invention provides a glass made from the glass composition of the first aspect of the present invention, the glass having the following properties:

a. maximum stress value sigma of bending test_maxNot less than 80 MPa; and

b. maximum strain epsilon of bending test_max≥1500×10^-6。

Preferably, the glass has a maximum stress value σ in bending test_maxMore preferably, ≧ 100MPa, further preferably σ_max120MPa or more, more preferably sigma_maxNot less than 130 MPa; preferably, the maximum strain amount ε of bending test_max≥1600×10^-6Preferably, epsilon_max≥1700×10^-6More preferably,. epsilon_max≥1800×10^-6。

Preferably, the glass also has the following properties:

(1) a temperature T corresponding to a viscosity of 200 poise₂₀₀1630 ℃ or less, preferably T₂₀₀≤1627℃；

(2) Liquidus temperature T_L1200 ℃ or less, preferably T_L≤1130℃；

(3) Strain point T_st650 ℃ and 730 ℃, preferably 680℃ -700 ℃, more preferably 680 ℃ to 695 ℃;

(4) young's modulus is more than or equal to 72GPa and specific modulus is more than or equal to 30GPa (g/cm)³) Preferably, the Young's modulus is more than or equal to 73GPa and the specific modulus is more than or equal to 30.5 GPa/(g/cm)³) (ii) a And

(5) the corrosion rate of hydrofluoric acid is 4-6.5mg/cm²Preferably 4.5-5.3mg/cm²More preferably 4.5-5.2mg/cm²。

According to the invention, the glass also has the following properties:

(6) the density is less than 2.49g/cm³Preferably less than 2.42g/cm³；

(7) A coefficient of thermal expansion in the range of 50-350 ℃ of less than 38 x 10^-7/° C, preferably less than 36X 10^-7/℃；

(8) A transmittance at a wavelength of 308nm of not less than 50%, preferably not less than 70%;

(9) surface tension of less than or equal to 370mN/m, preferably less than or equal to 360mN/m at 1200 ℃;

(10) vickers hardness greater than or equal to 580kgf/cm²Preferably ≥ 620kgf/cm²；

(11) The refractive index nD is less than or equal to 1.53, preferably less than or equal to 1.52.

The glass according to the second aspect of the invention has a high mechanical strength (i.e. high maximum stress value in bending test and maximum strain in bending test) combined with a low density, a high chemical resistance (i.e. high chemical stability), a low thermal expansion coefficient (lower than 38 x 10)^-7/° c), higher strain point temperature, and the like.

In a third aspect, the present invention provides a method of making glass from the glass composition of the first aspect of the invention, the method comprising: the glass composition of the first aspect of the present invention is subjected to melting, forming, annealing, and machining. The glass can be any shape of finished glass, such as a glass sheet.

In the process of the third aspect of the invention, the components of the composition are mixed together prior to melting the composition. The conditions for melting and forming can be selected according to the prior art, for example, the conditions for melting treatment include: the temperature is lower than 1630 ℃, and the time is longer than 1 h. The specific temperature and time can be determined by those skilled in the art according to practical situations, and are not described herein.

In the method according to the third aspect of the present invention, it is preferable that the annealing condition includes: the temperature is higher than 720 ℃ and the time is more than 0.1 h. The specific annealing temperature and time can be determined by those skilled in the art according to practical situations, and are not described herein again.

In the method according to the third aspect of the present invention, the machining treatment is not particularly limited, and various machining methods that are generally used in the art may be used, and for example, the product obtained by the annealing treatment may be cut, ground, polished, or the like.

Preferably, the method further comprises: and carrying out secondary fusion thinning treatment on the product obtained by the mechanical processing treatment.

Preferably, the conditions of the machining process or the secondary fusion draw process are controlled to produce glass sheets having a thickness of less than 0.1 mm.

The alkali-free glass can be used for preparing display devices and/or solar cells, and is particularly suitable for preparing substrate glass substrate materials and/or glass film layer materials for screen surface protection of flat panel display products, substrate glass substrate materials and/or surface packaging glass materials and/or glass film layer materials for screen surface protection of flexible display products, substrate glass substrate materials of flexible solar cells, safety glass, bulletproof glass, intelligent automobile glass, intelligent traffic display screens, intelligent show windows and intelligent card tickets, and other application fields requiring glass materials with high thermal stability and mechanical stability.

The present invention will be described in detail below by way of examples.

In the following examples, each raw material used was commercially available unless otherwise specified, and the test methods used were those conventionally used in the art unless otherwise specified.

Measured with reference to ASTM C-693Glass density in g/cm³。

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

The Young's modulus of the glass is measured in GPa according to ASTM C-623; the specific modulus is calculated from the ratio of Young modulus to density and has the unit of GPa/(g/cm)³)。

Glass high temperature visco-temperature curve was determined using a rotary high temperature viscometer with reference to ASTM C-965, where 200P viscosity corresponds to temperature T₂₀₀In units of; 35000P viscosity temperature T₃₅₀₀₀In units of ℃.

Determination of glass liquidus temperature T Using the ladder furnace method with reference to ASTM C-829_LIn units of ℃.

Determination of glass annealing Point T Using an annealing Point Strain Point tester with reference to ASTM C-336_aAnd strain point T_stIn units of ℃.

The Vickers hardness of the glass was measured in kgf/cm using a Vickers hardness tester according to ASTM E-384²。

The surface tension of the glass at 1200 ℃ was measured in mN/m using a high temperature surface tension meter (model ZLXS-II, Asahi New technology Co., Ltd., Beijing).

The refractive index n of the glass was measured at room temperature using a WAY-2S Abbe refractometer from Shanghai optical Instrument plant_D。

The transmittance of the glass is measured by using an ultraviolet-visible spectrophotometer, the thickness of the glass sample is 0.5mm, and the transmittance at 308nm is respectively taken, wherein the unit is percent.

The hydrofluoric acid etching rate refers to the weight loss of an alkali-free glass substrate in a 10 wt% HF solution at 20 deg.C for 20min, and is denoted as CHF, in mg/cm²。

The bending test refers to a three-point bending strength test, and is measured by using a WAW-500W model bending strength tester manufactured by Shenzhen Sansi longitudinal and transverse science and technology Limited. Wherein the length of the glass sample is more than or equal to 120mm, the thickness of the glass plate is more than 0.1mm, the diameters of the lower support and the upper pressure rod are 3mm, the span L of the lower support is 110mm,the rate of load drop of the glass plate sample was 10 mm/min. Maximum strain epsilon of bending test_maxRefers to the maximum failure strain of the glass substrate in the process of being stressed to fracture; maximum stress value sigma of bending test_maxRefers to the maximum failure stress in MPa during the process of breaking the glass substrate. Epsilon_maxAnd σ_maxRespectively according to the following formula:

wherein F is the maximum load when the glass plate sample is broken, and the unit is N; l is a lower support span in mm; d is the maximum displacement of the glass plate sample when the glass plate sample is broken, and the unit is mm; b is the width of the glass plate sample, and the unit is mm; h is the thickness of the glass plate sample in mm.

Examples 1 to 24 and comparative examples 1 to 3

According to the formulation of the alkali-free glass composition shown in Table 1, the components were mixed well, then heated at 1600 ℃ for 10 hours with slow stirring. Pouring molten glass into a stainless steel cast iron grinding tool to form a specified block-shaped glass product, and then putting the glass product in an annealing furnace at a corresponding annealing point T_aAnnealing for 2 hours, turning off the power supply and cooling to 25 ℃. And cutting, grinding and polishing the glass product, cleaning with deionized water and drying to obtain a glass finished product with the thickness of 0.5 mm. The various properties of each finished glass were measured and the results are shown in Table 2.

In Table 1, "-" indicates the absence of the component or the absence of the parameter.

As can be seen from the results in tables 1-3, the glass compositions of the present invention produced glass (e.g., examples 1-23) having maximum stress values σ for bending tests_maxNot less than 80 MPa; maximum strain epsilon of bending test_max≥1500×10^-6And a low coefficient of thermal expansion of not more than 38X 10^-7/° C, the strain point temperature of the glass is higher than 650 ℃ and the density is lower than 2.49g/cm³The performance is significantly better than that of the glass described in the comparative example.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. An alkali-free glass composition comprising: the glass composition comprises 58-62, based on the total weight of the alkali-free glass composition.6 wt% SiO₂16-18.5 wt% of Al₂O₃7-13 wt% of B₂O₃+P₂O₅0.7-3.5 wt% of MgO, 4-8 wt% of CaO, 0.1-4 wt% of SrO, 0-2.5 wt% of BaO, 0-4 wt% of ZnO, less than 0.05 wt% of R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of the contents of O;

wherein R' O/(B)₂O₃+P₂O₅) The weight ratio of (A) to (B) is more than 0.9 and less than R' O/(B)₂O₃+P₂O₅) Less than 1.3, R' O is the sum of the contents of MgO, CaO, SrO, BaO and ZnO;

wherein, B₂O₃/(B₂O₃+P₂O₅) The weight ratio of (A) is more than 0.1;

wherein the weight ratio of MgO/CaO satisfies that MgO/CaO is more than 0.1 and less than 0.9;

wherein the weight ratio of SrO/CaO satisfies that SrO/CaO is more than 0.01.

2. The composition of claim 1, wherein the glass composition comprises 61-62.3 wt% SiO₂17-18 wt% of Al₂O₃8.8-11 wt% of B₂O₃+P₂O₅1.1-2.7 wt% of MgO, 5.4-7.7 wt% of CaO, 1.6-3.6 wt% of SrO, 0 wt% of BaO, 0 wt% of ZnO, less than 0.05 wt% of R₂O, wherein R₂O is Li₂O、Na₂O、K₂Sum of O content.

3. The composition according to claim 1 or 2, wherein B₂O₃/(B₂O₃+P₂O₅) The weight ratio of (A) to (B) is more than 0.8₂O₃/(B₂O₃+P₂O₅)≤1。

4. The composition according to claim 1 or 2, wherein 1.0 < R' O/(B)₂O₃+P₂O₅)＜1.2。

5. Composition according to claim 1 or 2, wherein the weight ratio MgO/CaO satisfies 0.15 < MgO/CaO < 0.5.

6. Composition according to claim 1 or 2, wherein the SrO/CaO weight ratio satisfies 0.2 < SrO/CaO < 0.6.

7. The composition according to claim 6, wherein the SrO/CaO weight ratio satisfies 0.3 < SrO/CaO < 0.45.

8. Composition according to claim 1 or 2, wherein SiO₂+Al₂O₃The sum of the weight contents Q is more than 75 wt%.

9. The composition of claim 8, wherein the SiO₂+Al₂O₃The sum Q of the weight contents of (A) is more than 75 wt% and less than 82 wt%.

10. The composition of claim 9, wherein the SiO₂+Al₂O₃The sum Q of the weight contents of (A) is more than 78 wt% and less than 81 wt%.

11. A glass made from the glass composition of any of claims 1-10, said glass having the following properties:

a. maximum stress value sigma of bending test_maxNot less than 80 MPa; and

b. maximum strain epsilon of bending test_max≥1500×10^-6；

The glass is made by a process comprising: melting, molding, annealing and machining the glass composition;

the conditions under which the glass composition is melted include: the temperature is lower than 1630 ℃, and the time is longer than 1 h;

the conditions of the annealing treatment include: the temperature is higher than 720 ℃, and the time is more than 0.1 h;

and after the annealing treatment is finished, cooling the glass along with the furnace.

12. The glass of claim 11, wherein the glass has the following properties:

(1) a temperature T corresponding to a viscosity of 200 poise₂₀₀≤1630℃，

(2) Liquidus temperature T_L≤1200℃，

(3) Strain point T_stAt a temperature of 650 plus 730 ℃,

(4) young modulus is more than or equal to 72GPa and specific modulus is more than or equal to 30 GPa/(g/cm)³) And are and

(5) the corrosion rate of hydrofluoric acid is 4mg/cm²-6.5mg/cm²。

13. The glass of claim 12, wherein the glass has the following properties:

(1) a temperature T corresponding to a viscosity of 200 poise₂₀₀≤1627℃，

(2) Liquidus temperature T_L≤1130℃，

(3) Strain point T_stThe temperature of the mixture is between 680 and 695 ℃,

(4) young modulus is more than or equal to 73GPa and specific modulus is more than or equal to 30.5 GPa/(g/cm)³) And are and

(5) the corrosion rate of hydrofluoric acid is 4.5mg/cm²-5.3mg/cm²。

14. Use of a glass according to any one of claims 11 to 13 in a display device or a solar cell.