CN108658454A - A kind of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free and preparation method thereof, high Al₂O₃, low SiO₂Replace MgO with the parts ZnO, with MgO, ZnO, Al₂O₃、SiO₂And borate is raw material, B₂O₃It is introduced by boric acid, zinc borate, antifungin or aluminium borate, the content of oxide is：MgO：5.85%~12.37%；ZnO：0.13%~11.81%；Al₂O₃：29.60%~31.45%；SiO₂：49.71%~52.83%；B₂O₃：3.03%~3.22%；MgO and ZnO gross mass contents are 12.50%~17.66%.Preparation process of the present invention is simple, fusion temperature is low, glass low-density, low thermal coefficient of expansion, low-dielectric loss and moderate dielectric constant obtained, is used for hybrid circuit substrate, encapsulating material or flat-panel monitor.

Description

A kind of alkali-free high aluminum borosilicate glass with low thermal expansion coefficient and preparation method thereof

technical field

The invention relates to a low thermal expansion coefficient alkali-free high-alumina borosilicate glass and a preparation method thereof, in particular to a glass material with a low thermal expansion coefficient, low dielectric loss and dielectric constant and a preparation method thereof, belonging to the field of glass technology.

technical background

MgO-Al ₂ O ₃ -SiO ₂ (MAS) system glass is a very important scientific research due to its excellent thermal shock resistance, thermal stability, low thermal expansion system, high strength and excellent dielectric properties. Value and economic value of glass. In addition to the excellent mechanical properties and chemical stability of ordinary oxide glasses, the MAS system glass also has its unique optical properties, and its high strain point (≥700°C) is not available in other system glasses. People have been actively researching and developing MAS-based glasses. In recent years, they have been widely used in glass materials such as packaging materials, corrosion-resistant containers, glass fibers, and flat panel displays. In particular, the rapid development of high-end liquid crystal display TFT-LCD, due to its ultra-high requirements on the performance of flat glass (strict environment without alkali metal, suitable thermal expansion coefficient, etc.), makes the alkali-free boroaluminosilicate glass system Development research is of great significance.

Most TFT-LCD glass substrates use alkali-free boroaluminosilicate glass, that is, glass that does not contain alkali metal oxides (such as Li ₂ O, Na ₂ O, K ₂ O, etc.). However, in order to reduce the melting temperature of the glass and adjust the performance of the glass, it is necessary to introduce a certain amount of alkaline earth metal oxides (such as MgO, CaO, SrO, BaO, etc.). The main reasons are as follows: First, the glass transistor liquid crystal display panel has to undergo relatively high temperature treatment during the manufacturing process; second, ordinary soda-alkali glass contains more alkali metal ions, which is very likely to damage the TFT-LCD glass substrate performance. Therefore, the substrate glass is alkali-free, and the content of alkali metals generally does not exceed one thousandth of the glass components. Before making a liquid crystal display, the substrate glass needs to go through a series of physical and chemical processing. In this process, there are many procedures where the processing temperature may reach 600°C or even higher. At this time, if the composition of the substrate glass contains a large amount of alkali metal ions, the diffusion rate of alkali metal ions is very fast. Under the action of such a high temperature, the alkali metal ions will be separated from the network structure of the substrate glass and diffuse into various coatings and semiconductor materials on the surface of the substrate glass, which will seriously affect the performance of the coating and semiconductor materials, thereby reducing the display performance. The display effect and life of the display, what's more, it will cause the display device to fail or be destroyed. At present, the control of alkali metal ion content is mainly to control the alkali metal content in raw materials. On this basis, in the process of glass processing, the introduction of other alkali metal impurities should be avoided as much as possible.

At the same time, in the manufacturing process of the glass substrate, the thermal expansion coefficient of the substrate glass must match the semiconductor material in the thin film transistor array, that is, polysilicon and amorphous silicon materials. During the processing of the substrate glass, the thermal stress generated by the temperature can be mutually offset. At the same time, there are many thin film materials on the substrate glass. These thin film materials may also have certain deformations during the processing of the substrate glass. The stretching force may cause the film to break, damage the display, and seriously shorten the display life of the display. Generally speaking, the ideal range of the thermal expansion coefficient of the TFT-LCD substrate glass is 30×10 ^-7 /°C to 40×10 ^-7 /°C.

CN 106488889 A discloses an alkali metal-free boroaluminosilicate glass used in flat-panel display devices, and its oxide mass percentages are as follows: SiO ₂ : 57-61; Al ₂ O ₃ : 17.5-20.5; B ₂ O ₃ : 5-8; MgO: 1-5; CaO: 3-9; SrO: 0-6; BaO: 0-6.5. The alkali-free glass is prepared by the overflow down-draw method, and the obtained glass has the following properties: the annealing point is higher than or equal to 735°C, the thermal expansion coefficient CTE is less than 39×10 ^-7 /°C in the temperature range of 25-300°C, and the Young's modulus is greater than or equal to Equal to 77GPa, density less than or equal to 2.55g/cm ³ . The patent is characterized by a relatively high _SiO2 content (≥57wt%), a low _Al2O3 content ( _≤20.5wt %), and four alkaline earth metal oxides including heavy metal barium ions, and does not involve ZnO The substitution of MgO does not involve other properties such as alkali-free high-alumina borosilicate glass and glass dielectric constant and dielectric loss.

CN 101591141 A discloses an alkali-free boroaluminosilicate glass used for preparing display glass substrates. The molar percentages of oxides are as follows: SiO ₂ : 64-68.2; Al ₂ O ₃ : 11-13.5; B ₂ O ₃ : 5-9; MgO: 2-9; CaO: 3-9; SrO: 1-5; BaO: 0-6.5. The alkali-free glass is prepared by the overflow down-draw method, and the resulting glass has the following properties: a melting temperature lower than or equal to 1620°C, an annealing point higher than or equal to 725°C, and a linear coefficient of thermal expansion CTE within the temperature range of 0° to 300°C Less than 40×10 ^-7 /°C. This patent is characterized by high SiO ₂ content (≥64mol%), low Al ₂ O ₃ content (≤13.5mol%), and four alkaline earth metal oxides including heavy metal barium ions, and does not involve ZnO on The substitution of MgO does not involve alkali-free high-alumina borosilicate glass and other properties such as dielectric constant and loss of glass. Due to the high content of SiO ₂ and the high degree of polymerization of [SiO ₄ ] tetrahedrons in the melt, there are bound to be problems such as high viscosity at high temperature, difficult removal of bubbles, and difficulty in melting.

CN 104276754 A discloses a silicate glass substrate for flat panel displays, the mass percentage of oxides is as follows: SiO ₂ : 64-70; Al ₂ O ₃ : 12-16; MgO: 0-10; B ₂ O ₃ : 3 to 8.5; CaO: 6.5 to 9.5; SrO: 2.5 to 5; SnO: 0.02 to 0.1; and wherein: SrO/(CaO+SrO)<0.4, Al ₂ O ₃ /(CaO+SrO)>1.0. The preparation process is as follows: according to the design ratio, weigh the chemical raw materials, stir and mix them evenly, then melt the mixed raw materials, use platinum rods to stir and discharge air bubbles, homogenize the glass liquid, and then lower the temperature to the required level for molding. The forming temperature range of the glass substrate, through the principle of annealing, produces the thickness of the glass substrate required by the flat-panel display, and then performs cold processing on the formed glass substrate. The obtained glass has a higher strain point (714-758°C), a lower melting temperature (1584-1626°C), a lower liquidus temperature (1080-1120°C), and is environmentally friendly. This patent is characterized by high SiO ₂ content (≥64wt%), low Al ₂ O ₃ content (≤16wt%), and three kinds of alkaline earth metal oxides. Alkali high alumina borosilicate glass and other properties such as dielectric constant and loss of glass. Due to the high content of SiO ₂ and the high degree of polymerization of [SiO ₄ ] tetrahedrons in the melt, there are bound to be problems such as high viscosity at high temperature, difficult removal of bubbles, and difficulty in melting.

Aiming at the problems of high melting temperature, high viscosity, and difficult to remove bubbles in the preparation process of existing similar glasses, the patent of the present invention has achieved low SiO ₂ content (≤52.83wt%) and high Al ₂ O ₃ content ( ≥29.5wt%), contains an alkaline earth metal oxide MgO, and is characterized in that part of the ZnO replaces MgO, and the alkali-free high-alumina borosilicate glass with excellent comprehensive properties is prepared by the traditional melt cooling method.

Contents of the invention

The object of the present invention is to provide a low thermal expansion coefficient alkali-free high-alumina borosilicate glass and a preparation method thereof. The alkali-free high-alumina borosilicate glass material includes the following components in terms of mass percentage: MgO ZnO: 0.13% to 11.81%; Al ₂ O ₃ : 29.60% to 31.45%; SiO ₂ : 49.71% to 52.83%; B ₂ O ₃ : 3.03% to 3.22%. Wherein, the total mass percentage of MgO and ZnO is 12.50%-17.66%, and the mass ratio of MgO and ZnO satisfies 0.01<ZnO/MgO<2.02.

The present invention is based on MgO, Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ , wherein the total content of Al ₂ O ₃ , SiO ₂ and B ₂ O ₃ is more than 80 wt%. The present invention aims at the problems that MgO, Al ₂ O ₃ , SiO ₂ , and B ₂ O ₃ glasses have high melting temperature, high viscosity, and difficulty in removing bubbles. Adjust the proportion relationship between them, reduce the content of SiO ₂ in the composition, increase the content of Al ₂ O ₃ , replace magnesium oxide with zinc oxide, and the prepared glass has a lower thermal expansion coefficient, about 3.434～3.891×10 ^{- 6} /°C (25-600°C), and the glass has moderate dielectric constant, low dielectric loss and density.

A method for preparing alkali-free high-alumina borosilicate glass with a low coefficient of thermal expansion, comprising the following process steps:

Calculate the corresponding raw material dosage of MgO, ZnO, Al ₂ O ₃ , SiO ₂ and borate according to the design formula;

Accurately weigh and fully mix all raw materials to make glass batches;

Put the glass batch material into the crucible, heat it to the melting temperature, and keep it warm to get a uniform glass melt;

Pour the glass melt into a preheated stainless steel mold for molding, annealing, and eliminate the residual stress in the glass;

After the annealing of the glass is completed, it is cooled to room temperature to obtain the alkali-free glass.

In the step 3), heat at a heating rate of 5° C./min to a melting temperature of 1600° C. to 1650° C., and keep the temperature for 2 to 3 hours.

The temperature of the annealing treatment in the step 4) is 680°C, and the annealing time is 6-10 hours.

The crucible is platinum crucible, corundum crucible or quartz crucible.

Main points of the present invention are as follows:

1. Low SiO ₂ , high Al ₂ O ₃ : The mass percentage of SiO ₂ in the present invention ranges from 49.71% to 52.83%. Compared with the SiO ₂ content of glass in the same field exceeding 57wt%, the SiO ₂ content in the present invention Relatively low; the mass percent content of Al ₂ O ₃ in the present invention ranges from 29.60% to 31.45%. Compared with the Al ₂ O ₃ content of glass in the same field which is less than 20.5wt%, the Al ₂ O ₃ content in the present invention is very high.

SiO ₂ is a network former oxide, and in the melt, Si ⁴⁺ exists in the aggregated form of [SiO ₄ ] tetrahedron. The higher the SiO ₂ content, the higher the polymerization degree of [SiO ₄ ] tetrahedron in the melt, and the lower the thermal expansion coefficient of the glass obtained. However, the higher the _SiO2 content, the greater the viscosity of the glass melt, resulting in process problems such as difficult removal of bubbles and difficulty in melting. Al ₂ O ₃ is a network intermediate oxide, and the strength of the Al-O bond is weaker than that of the Si-O bond. Therefore, the combination of low SiO ₂ and high Al ₂ O ₃ content can reduce the glass in the melting process. High-temperature viscosity is good for air bubble removal and homogenization. At the same time, due to the introduction of a certain amount of alkaline earth metal oxides, there are a large number of discontinuities in the [SiO ₄ ] tetrahedral polymerization network structure (that is, [SiO ₄ ] and [SiO ₄ ] are not directly connected), under certain conditions, Al ^{3 +} can enter these network discontinuities in the form of [AlO ₄ ] and participate in the reconstruction of the glass network structure, thereby endowing the glass with low thermal expansion coefficient, high chemical stability and high strength.

2. Part of ZnO replaces MgO in the glass composition: MgO is an oxide outside the network. When its content is high, the expansion coefficient of the glass increases, and it may make the glass easy to devitrify. If the MgO is too low, the glass melt The viscosity will increase and the meltability will decrease. Compared with MgO, the role of ZnO in the oxide glass structure depends on the content of ZnO. Zn ²⁺ belongs to the transition metal ion structure, with 18 electrons in the outer layer, and the electron cloud is easy to deform, and its covalent composition can be increased through polarization, and it has a stronger ability to compete with the glass network to form bulk ions for oxygen ions. Therefore, ZnO replaces MgO It is easier to cause the depolymerization of the [SiO ₄ ] tetrahedron aggregation structure, thereby reducing the viscosity of the glass melt and enhancing the glass melting effect. At the same time, due to the strong mutual interference between the compositions, a small amount of ZnO replacing MgO can increase the difference between Tg and Tc, thereby enhancing the glass-forming ability and delaying the crystallization process.

3. There is no need to add clarifier: At present, the preparation of alkali-free aluminosilicate glass mostly adds glass clarifiers such as As ₂ O ₃ , Sb ₂ O ₃ , Cl ₂ or F ₂ to remove air bubbles in the glass. The addition of clarifiers not only increases the difficulty and cost of the process, but also often introduces toxic and harmful components, such as As and Sb. The invention rationally designs the glass components and the preparation process, and prepares the alkali-free aluminosilicate glass without visible bubbles without adding a clarifier.

The invention provides a method for preparing alkali-free high-alumina borosilicate glass with a low thermal expansion coefficient, using analytically pure magnesium oxide, silicon dioxide, aluminum oxide, borate and zinc oxide as raw materials, according to the pre-designed Proportioning First, the weighed raw materials are fully mixed to make a glass batch, and the alkali-free high-alumina borosilicate glass is obtained through the traditional melt cooling method and annealing process.

A kind of alkali-free high-alumina borosilicate glass and preparation method thereof of low thermal expansion coefficient prepared by the present invention also include the following preferred schemes:

In the preferred scheme, the raw material mixing mode is: at first the weighed MgO is fully mixed with ZnO, then the glass frit obtained by mixing the two is added into other raw materials and further mixed to form a glass batch, which has a better substitution effect.

In the preferred scheme, the crucible used for assembling the materials is a platinum crucible.

In the preferred scheme, the melting method is to melt the glass frit, water quench, and remelt once to improve the uniformity of the melt.

In the preferred solution, the cooling method after the annealing is furnace cooling.

Through a large number of experiments and repeated tests on the relationship between the ratio of each component and the glass structure and performance, the present invention successfully realizes the optimization of each component of the glass, and finally obtains alkali-free high-aluminum boron with low thermal expansion coefficient Silicate glass, its main properties are: thermal expansion coefficient of 3.434～3.891×10 ^-6 /℃, glass transition temperature of 771～804℃, crystallization peak temperature of 1036～1063℃, transmittance of visible light and near infrared region The glass density is 2.578-2.712g/cm ³ , the glass hardness is 5.6-6.3GPa, the bending strength is 87-97MPa, the compressive strength is 48-62MPa, and the dielectric constant is 6.32-6.60. The dielectric loss is 0.0029 to 0.0043. In addition, the alkali-free high-alumina borosilicate glass material has simple preparation process, low melting temperature, no need to add clarifier, low raw material cost, and can meet the requirements of industrial production.

Description of drawings

[Fig. 1] is the DSC curve diagram of the glass powder of the alkali-free high aluminum borosilicate glass material prepared in Example 1 of the present invention;

[ Fig. 2 ] is a graph showing the transmittance curves in the wavelength range of 200-1100 nm of the alkali-free high-alumina borosilicate glass materials prepared in Examples 1-5 of the present invention.

Detailed ways

Below in conjunction with embodiment content of the present invention will be further described, but should not limit protection scope of the present invention with this.

Example 1

A kind of alkali-free high-alumina borosilicate glass with low thermal expansion coefficient prepared in this embodiment comprises the following oxides in mass percentage: MgO: 12.37%, ZnO: 0.13%, Al ₂ O ₃ : 31.45%, SiO ₂ : 52.83%, B ₂ O ₃ : 3.22%. Accurately weigh the corresponding raw materials, mix all the raw materials fully and put them into a platinum crucible, raise the temperature to 1650 °C at a heating rate of 5 °C/min in a well-sealed silicon-molybdenum rod resistance furnace, and keep it for 3 hours to obtain a uniform glass melt ; Then pour the glass melt into a preheated stainless steel mold for molding, anneal at 680°C for 10 hours, and cool to room temperature with the furnace, and finally obtain a colorless, transparent, uniform, and bubble-free bulk glass. FIG. 1 is a DSC curve diagram of the alkali-free high aluminoborosilicate glass material prepared in Example 1.

Example 2

A kind of alkali-free high-alumina borosilicate glass with low thermal expansion coefficient prepared in this embodiment comprises the following oxides in mass percentage: MgO: 12.09%, ZnO: 0.63%, Al ₂ O ₃ : 31.38%, SiO ₂ : 52.69%, B ₂ O ₃ : 3.21%. Accurately weigh the corresponding raw materials, mix all the raw materials fully and put them into a corundum crucible, raise the temperature to 1650°C at a heating rate of 5°C/min in a well-sealed molybdenum silicon rod resistance furnace, and keep it for 3 hours to obtain a uniform glass melt , and then pour the glass melt into a preheated stainless steel mold for molding, anneal at 680°C for 10 hours, and cool to room temperature with the furnace, and finally obtain a colorless, transparent, uniform, and bubble-free bulk glass.

Example 3

An alkali-free high-alumina borosilicate glass with a low thermal expansion coefficient prepared in this example comprises the following oxides in mass percent: MgO: 11.74%, ZnO: 1.25%, Al ₂ O ₃ : 31.28%, SiO ₂ : 52.53%, B ₂ O ₃ : 3.20%. Accurately weigh the corresponding raw materials, mix all the raw materials fully and put them into a quartz crucible, raise the temperature to 1650 °C at a heating rate of 5 °C/min in a well-sealed silicon-molybdenum rod resistance furnace, and keep it for 2 hours to obtain a uniform glass melt , and then pour the glass melt into a preheated stainless steel mold for molding, anneal at 680°C for 10 hours, and cool to room temperature with the furnace, and finally obtain a colorless, transparent, uniform, and bubble-free bulk glass.

Example 4

A low thermal expansion coefficient alkali-free high-alumina borosilicate glass prepared in this example comprises the following oxides: MgO: 9.04%, ZnO: 6.09%, Al ₂ O ₃ : 30.51%, SiO ₂ : 51.24%, B ₂ O ₃ : 3.12%. Accurately weigh the corresponding raw materials, mix all the raw materials fully and put them into a corundum crucible, raise the temperature to 1620°C at a heating rate of 5°C/min in a well-sealed molybdenum silicon rod resistance furnace, and keep it for 3 hours to obtain a uniform glass melt , Pour the glass melt into a preheated stainless steel mold for molding, anneal at 680°C for 8 hours, and cool to room temperature with the furnace, and finally obtain a colorless, transparent, uniform, and bubble-free block glass.

Example 5

A kind of alkali-free high-alumina borosilicate glass with low thermal expansion coefficient prepared in this embodiment comprises the following oxides in mass percent: MgO: 5.85%, ZnO: 11.81%, Al ₂ O ₃ : 29.60%, SiO ₂ : 49.71%, B ₂ O ₃ : 3.03%. Accurately weigh the corresponding raw materials, mix all the raw materials fully and put them into a quartz crucible, raise the temperature to 1600 °C at a heating rate of 5 °C/min in a well-sealed silicon-molybdenum rod resistance furnace, and keep it for 2 hours to obtain a uniform glass melt , Pour the glass melt into a preheated stainless steel mold for molding, anneal at 680°C for 6 hours, and cool to room temperature with the furnace, and finally obtain a colorless, transparent, uniform, and bubble-free block glass.

The density of the glass was measured by the Archimedes method with deionized water as the medium. The STA449C synchronous thermal analyzer was used to measure the crystallization peak temperature and glass transition temperature of the glass from room temperature to 1200 °C under air atmosphere, and calculate ΔT. The coefficient of thermal expansion of glass samples from room temperature to 600 °C was measured using a thermal dilatometer (Netzsch DIL 402EP). The transmittance of the glass sample at room temperature in the wavelength range of 200-1100nm was measured by an ultraviolet-visible-near-infrared spectrophotometer (U-4100). The Vickers hardness of the glass samples was tested with a microhardness tester (DHV-1000) and converted into GPa. The flexural strength and compressive strength of the glass samples were measured using a universal testing machine (CCS-44100). The dielectric constant and dielectric loss of glass samples at room temperature at 1kHz were measured by Agilent 4294A precision impedance analyzer. See Table 1 for the performance parameters of the glass prepared in Examples 1 to 5 of the present invention. The transmittance curves of the alkali-free high aluminum borosilicate glass materials prepared in Examples 1-5 in the wavelength range of 200-1100nm, 1-5 in Fig. 2 are the results of Examples 1-5 respectively.

Table 1 The performance parameters of the alkali-free glass prepared in Examples 1 to 5

Claims (6)

1. a kind of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free, it is characterised in that：The glass material belongs to ZnO-MgO- Al₂O₃-SiO₂-B₂O₃System, high-content Al₂O₃, low content SiO₂And the parts ZnO substitution MgO, each oxide in glass raw material Mass percentage composition is：MgO：5.85%~12.37%；ZnO：0.13%~11.81%；Al₂O₃：29.60%~ 31.45%；SiO₂：49.71%~52.83%；B₂O₃：3.03%~3.22%；Alkali metal containing does not aoxidize in the glass composition Object.

2. a kind of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free according to claim 1, it is characterised in that：MgO Gross mass percentage composition with ZnO is 12.50%~17.66%, and the mass ratio of the MgO and ZnO meets 0.01<ZnO/ MgO<2.02；Without adding fining agent in glass composition.

3. a kind of preparation method of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free according to claim 1 or 2, It is characterized in that, comprises the following steps that：

1) corresponding MgO, ZnO, Al are calculated by component design₂O₃、SiO₂, each raw material dosage of borate, to analyze pure zirconia Magnesium, silica, alundum (Al2O3), borate and Zinc oxide powder are raw material；Wherein, B₂O₃By boric acid, zinc borate, antifungin Or boric acid aluminium borate introduces, and as fluxing agent；Borate while introducing portion ZnO, MgO, Al₂O₃；

2) by each raw material accurate weighing, be sufficiently mixed, glass batch is made；

3) glass batch is fitted into crucible, is heated to fusion temperature, kept the temperature, obtain uniform glass melt；

4) glass melt is poured into the stainless steel mould of preheating and is molded, annealed, eliminate the residual stress in glass；

5) it after glass annealing, is cooled to room temperature, the alkali-free glass is made.

4. a kind of preparation method of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free according to claim 3, special Sign is：1600 DEG C~1650 DEG C of melting temperature is heated to the heating rate of 5 DEG C/min in step 3), keeps the temperature 2~3h.

5. a kind of preparation method of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free according to claim 3, special Sign is：The temperature of step 4) annealing is 680 DEG C, and annealing time is 6~10h.

6. a kind of preparation method of high aluminium borosilicate glass of low thermal coefficient of expansion alkali-free according to claim 3, special Sign is：The crucible is platinum crucible, corundum crucible or silica crucible.