CN111285603B

CN111285603B - Glass

Info

Publication number: CN111285603B
Application number: CN201911238186.3A
Authority: CN
Inventors: 铃木良太
Original assignee: Nippon Electric Glass Co Ltd
Current assignee: Nippon Electric Glass Co Ltd
Priority date: 2018-12-07
Filing date: 2019-12-05
Publication date: 2023-08-22
Anticipated expiration: 2039-12-05
Also published as: JP2025039878A; CN111285603A; JP7445186B2; JP2024045688A; JP2021001104A; JP7626982B2

Abstract

The glass of the present invention is characterized by comprising SiO in mol% as a glass composition ₂ 40～70％、Al ₂ O ₃ 0～20％、B ₂ O ₃ 0～15％、Li ₂ O 0～15％、Na ₂ O 8.6～25％、K ₂ 0 to 1 percent of O, 2 to 15 percent of CaO, 1.5 to 15 percent of ZnO, and the softening point is below 720 ℃.

Description

Glass

Technical Field

The present invention relates to a low softening point glass suitable for curved surface processing (hot working).

Background

In recent years, as a head-mounted display, a device for projecting an image from a display hanging down from a visor, a glasses type device for displaying an external view and an image on a display, a device for displaying an image on a transparent light guide plate, and the like have been developed.

In the apparatus for displaying an image on a transparent light guide plate, the image displayed on the light guide plate can be observed while the external scenery is observed through the glasses. Further, the 3D display may be realized by a technique of projecting images different from each other in the left and right directions, or a technique of combining the eyes with the retina by using the lens of the eyes.

These devices require an optical member having a curved shape, which is manufactured by subjecting a glass plate (plate-like glass) to curved processing.

Prior art literature

Patent literature

Patent document 1: U.S. patent application publication No. 2017/283305 specification

Disclosure of Invention

Problems to be solved by the invention

However, when a glass plate is curved, it is necessary to heat-treat the glass plate to a temperature equal to or higher than the softening point, but when the heat treatment temperature is high, the life of a mold or the like for curved is shortened. When curved surface processing is performed at a low temperature in order to lengthen the life of the mold, the glass plate is less likely to be deformed by being contoured on the mold, and the dimensional stability is reduced.

Soda lime glass is generally used as a window glass, but it is difficult to accurately perform a curved surface processing because of a softening point of about 750 ℃.

On the other hand, if the softening point of the glass sheet is reduced to improve the curved surface workability, the glass becomes unstable, and devitrification of the glass is likely to occur during molding. In addition, the weather resistance is reduced, and the display image tends to become unclear.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass which can achieve a combination of curved surface workability, devitrification resistance, and weather resistance.

Means for solving the problems

The inventors repeatedly conducted various experiments, and found that: the present invention has been made to solve the above-described technical problems by strictly controlling the content of each component of glass and controlling the softening point to a predetermined range. That is, the glass of the present invention is characterized by comprising SiO in mol% as a glass composition ₂ 40～70％、Al ₂ O ₃ 0～20％、B ₂ O ₃ 0～15％、Li ₂ O 0～15％、Na ₂ O 8.6～25％、K ₂ 0 to 1 percent of O, 2 to 15 percent of CaO, 1.5 to 15 percent of ZnO, and the softening point is below 720 ℃. Here, "softening point" refers to a value measured based on the method of ASTM C338.

The glass of the present invention controls the content of each component in the above manner. This reduces the softening point and improves the devitrification resistance and weather resistance. In particular, the glass of the present invention has a ZnO content of 1.5 mol% or more. This reduces the softening point and improves weather resistance.

In the glass of the present invention, the softening point is controlled to 720 ℃. Thus, thermal degradation of the mold or the like is suppressed during the curved surface processing, and the glass plate is shaped to follow the shape of the mold, thereby easily changing the shape.

Furthermore, the glass of the present invention is preferably: as a glass composition, siO was contained in mol% ₂ 40～70％、Al ₂ O ₃ 4.4～20％、B ₂ O ₃ 0.1～13.6％、Li ₂ O 0～15％、Na ₂ O 13～25％、K ₂ 0 to 1% of O, 2 to 10% of CaO, 0 to 2% of SrO, 0 to 2% of BaO and 2 to 15% of ZnO, and the softening point is below 700 ℃.

The glass of the present invention is preferably plate-shaped.

The glass of the present invention is preferably subjected to a curved surface processing.

The surface roughness Ra of at least one surface of the glass of the present invention is preferably 0.1 to 5 μm. The term "surface roughness Ra" as used herein means an arithmetic mean roughness Ra as defined in JIS B0601-2001.

The glass of the present invention preferably has a thickness of 0.1 to 3mm.

In addition, at least one surface of the glass of the present invention preferably has a functional film, and the functional film is any one of an antireflection film, an antifouling film, a reflecting film, and a scratch-proof film.

The glass of the present invention is preferably formed by an overflow down-draw method.

In addition, the glass of the present invention preferably has a viscosity of 10 at the liquidus temperature ^4.6 dPa.s or more. Here, the "viscosity at liquid phase temperature" can be measured by the platinum ball pulling method. The "liquidus temperature" may be calculated by: after glass powder passing through a standard sieve of 30 mesh (500 μm) and remaining in a 50 mesh (300 μm) was charged into a platinum boat, the mixture was held in a temperature gradient furnace for 24 hours, and the crystallization temperature was measured.

The glass of the present invention is preferably used for a sensor member or an optical component member mounted on a vehicle.

The glass of the present invention is preferably used for a sensor or an optical component member mounted on a vehicle.

The glass of the present invention is preferably used for a sensor member for measuring a vehicle distance.

Detailed Description

The glass of the present invention is characterized by comprising SiO in mol% as a glass composition ₂ 40～70％、Al ₂ O ₃ 0～20％、B ₂ O ₃ 0～15％、Li ₂ O 0～15％、Na ₂ O 8.6～25％、K ₂ 0 to 1 percent of O, 2 to 15 percent of CaO and 1.5 to 15 percent of ZnO. The reason why the content of each component is limited as described above is as follows. In the description of the content of each component, the expression of% means mol% unless otherwise specified.

SiO ₂ Is a main component forming a glass skeleton. If SiO is ₂ If the content of (B) is too small, young's modulus, acid resistance and weather resistance tend to be low. Thus, siO ₂ The range of the lower limit is 40% or more, 45% or more, 50% or more, 52% or more, 55% or more, 57% or more, 60% or more, particularly 61% or more. On the other hand, if SiO ₂ If the content of (b) is too large, the softening point will be undesirably increased, devitrification crystals will be likely to precipitate, and the liquid phase temperature will be likely to rise. Thus, siO ₂ The upper limit of (c) is 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, 65% or less, 64% or less, 63% or less, 62% or less, particularly 61% or less.

Al ₂ O ₃ Is a component for improving Young's modulus and weather resistance. Al (Al) ₂ O ₃ The range of the lower limit of (2) is 0% or more, 1% or more, 3% or more, 4% or more, 4.4% or more, 4.6% or more, 5% or more, 5.5% or more, particularly 6% or more. On the other hand, if Al ₂ O ₃ If the content of (b) is too large, the high-temperature viscosity becomes high, and the curved surface workability tends to be low. Thus, al ₂ O ₃ The upper limit of (2) is 20% or less, less than 15%, or 12% or lessLess than 11%, less than 10%, especially less than 9%.

B ₂ O ₃ Is a component that forms a glass skeleton and functions as a flux. If B ₂ O ₃ If the content of (2) is too small, the liquid phase temperature tends to be low. Thus B is ₂ O ₃ The range of the lower limit is preferably 0% or more, 0.1% or more, 0.3% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more. On the other hand, if B ₂ O ₃ If the content of (2) is too large, the acid resistance and weather resistance tend to be lowered. Thus B is ₂ O ₃ The upper limit of (c) is 15% or less, 14% or less, 13.6% or less, 13% or less, 11% or less, 10% or less, 9.5% or less, 8.5% or less, 8% or less, 7.5% or less, 7% or less, particularly 6.5% or less.

Alkali metal oxide (Li) ₂ O、Na ₂ O、K ₂ O) is a component that lowers the softening point, but if introduced in a large amount, the viscosity of the glass is excessively lowered, and it is difficult to secure high liquid phase viscosity. In addition, young's modulus, weather resistance, and resistivity are liable to be lowered. Thus, li ₂ O、Na ₂ O and K ₂ The total amount of O is suitably in the lower limit range of 8.6% or more, 10% or more, 13% or more, 14% or more, 15% or more, 16% or more, 17% or more, particularly 18% or more, and is suitably in the upper limit range of 27% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, particularly 19% or less. Li (Li) ₂ The upper limit of the O content is 15% or less, 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly 0.1% or less. Na (Na) ₂ The preferable lower limit of O is 8.6% or more, 10% or more, 12% or more, 13% or more, 14% or more, 15% or more, 16% or more, particularly 17% or more, and the preferable upper limit is 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, particularly 18% or less. K (K) ₂ The preferable lower limit of O is 0% or more, particularly 0.1% or more, and the preferable upper limit is 5% or less, 3% or less, 2% or lessLess than 1%, less than 0.5%, especially less than 0.1%. K is the same as ₂ The introduction material of O contains a larger amount of harmful impurities (e.g., radiation releasing elements, coloring elements) than the introduction material of other components. Thus, K is a valuable point of view for removing harmful impurities ₂ The content of O is preferably 1% or less, 0.5% or less, particularly 0.1% or less.

Mole% ratio (Na ₂ O-Al ₂ O ₃ )/SiO ₂ Preferably more than 0, 0.05 or more, 0.1 or more, 0.11 to 0.5, 0.12 to 0.3, especially 0.15 to 0.25. If the molar percentage (Na ₂ O-Al ₂ O ₃ )/SiO ₂ If the softening point is too small, the softening point tends to rise. "(Na) ₂ O-Al ₂ O ₃ )/SiO ₂ "means from Na ₂ Subtracting Al from the O content ₂ O ₃ The amount obtained by dividing the content of (2) by SiO ₂ A value obtained by the content of (3).

If the mole% ratio Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ When the O) is controlled within the predetermined range, the softening point can be reduced and the devitrification resistance can be improved. Mole% ratio Na ₂ O/(Li ₂ O+Na ₂ O+K ₂ The suitable lower limit of O) is in the range of 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, especially more than 0.95. "Na" is a material ₂ O/(Li ₂ O+Na ₂ O+K ₂ O) "means Na ₂ The content of O divided by Li ₂ O、Na ₂ O and K ₂ Total amount of O.

If the mole% ratio of Al ₂ O ₃ /(Li ₂ O+Na ₂ O+K ₂ O) is controlled to a predetermined range, the softening point can be reduced while maintaining weather resistance. Mole% ratio of Al ₂ O ₃ /(Li ₂ O+Na ₂ O+K ₂ The preferable lower limit of O) is 0 or more, 0.1 or more, 0.2 or more, 0.25 or more, 0.3 or more, particularly, more than 0.35, and the preferable upper limit is 1.1 or less, 1.0 or less, 0.8 or less, 0.7 or less, 0.6 or less, particularly, 0.5 or less. "Al" is used to indicate ₂ O ₃ /(Li ₂ O+Na ₂ O+K ₂ O "means Al ₂ O ₃ Divided by Li content ₂ O、Na ₂ O and K ₂ Total amount of O.

MgO, caO, srO and BaO are components for lowering the softening point. However, when MgO, caO, srO, baO and ZnO are introduced in large amounts, the density becomes too high, the young's modulus tends to be lowered, and the high-temperature viscosity is lowered excessively, making it difficult to secure high-liquid-phase viscosity. Thus, the suitable lower limit range of the total amount of MgO, caO, srO and BaO is 2% or more, 2.5% or more, 3% or more, particularly 3.5% or more, and the suitable upper limit range is 20% or less, 18% or less, 15% or less, 12% or less, 10% or less, 8% or less, 6% or less, particularly 4% or less.

MgO is a component that reduces the softening point, and is a component that effectively increases Young's modulus among alkaline earth metal oxides. However, if the MgO content is too large, the devitrification resistance and weather resistance tend to be lowered. The preferable lower limit of MgO is 0% or more, 0.1% or more, particularly 0.5% or more, and the preferable upper limit is 15% or less, 10% or less, 8% or less, 5% or less, less than 3%, 2% or less, 1% or less, particularly 0.9% or less.

CaO is a component that lowers the softening point, and among alkaline earth metal oxides, it is a component that reduces the cost of raw materials because of relatively low cost of raw materials to be introduced. In addition, it is also a component for improving weatherability. However, if the CaO content is too large, the devitrification resistance and weather resistance tend to be lowered. The lower limit of CaO is preferably 2% or more, 3% or more, 3.1% or more, particularly 3.7% or more, and the upper limit is preferably 15% or less, 10% or less, 8% or less, 7% or less, 6% or less, particularly 5% or less.

The CaO content is preferably more than K ₂ O content, more preferably the ratio K ₂ O content is more than 1 mol%, preferably more than K ₂ The content of O is more than 2 mol%. If the CaO content is less than K ₂ The content of O makes it difficult to achieve both a low softening point and high devitrification resistance.

SrO is a component for improving the devitrification resistance, but if the content is too large, the component of the glass composition becomes unbalanced, and the devitrification resistance tends to be lowered instead. In addition, it is easy to mix harmful impurities from the introduced raw material. Thus, the upper limit of SrO is 10% or less, 3% or less, 2% or less, 1% or less, and particularly 0.1% or less.

BaO is a component for improving the devitrification resistance, but if it is contained in an excessive amount, the glass composition becomes unbalanced, and the devitrification resistance tends to be lowered instead. In addition, it is easy to mix harmful impurities from the introduced raw material. Thus, the upper limit of the BaO is 10% or less, 3% or less, 2% or less, 1% or less, and particularly 0.1% or less.

ZnO is a component that lowers the softening point and improves weatherability, but if it is contained in too much amount, the glass is liable to devitrify. Thus, the suitable lower limit of ZnO is 1.5% or more, 2% or more, 2.5% or more, 3% or more, particularly 3.5% or more, and the suitable upper limit is 15% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, particularly less than 4.8%.

If the mol% ratio CaO/(mgo+cao+sro+bao+zno) is controlled to be within a predetermined range, the softening point can be reduced while the raw material cost is reduced. The suitable lower limit range of the mol% ratio CaO/(MgO+CaO+SrO+BaO+ZnO) is 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, especially more than 0.8 and 0.95 or less. "CaO/(mgo+cao+sro+bao+zno)" means a value obtained by dividing the content of CaO by the total amount of MgO, caO, srO, baO and ZnO.

If the mol% ratio ZnO/(mgo+cao+sro+bao+zno) is controlled to be within a predetermined range, the weather resistance can be improved while maintaining the low softening property. The suitable lower limit range of the mol% ratio ZnO/(MgO+CaO+SrO+BaO+ZnO) is 0.1 or more, 0.11 to 1.0, 0.15 to 0.75, 0.2 to 0.55, 0.25 to 0.5, especially more than 0.3 and 0.4 or less. The term "ZnO/(mgo+cao+sro+bao+zno)" refers to a value obtained by dividing the content of ZnO by the total amount of MgO, caO, srO, baO and ZnO.

In addition to the above components, other components may be introduced. From the viewpoint of ensuring the effect of the present invention, the content of the other components than the above components is preferably 12% or less, 10% or less, 8% or less, and particularly preferably 5% or less, based on the total amount.

TiO ₂ And ZrO(s) ₂ Is a component for improving acid resistance. However, if TiO ₂ And ZrO(s) ₂ If the content of (b) is too large, the devitrification resistance and transmittance tend to be lowered. In addition, it is easy to mix harmful impurities from the introduced raw material. TiO (titanium dioxide) ₂ The upper limit of (c) is preferably 5% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly preferably less than 0.1%. ZrO (ZrO) ₂ The upper limit of (c) is preferably 5% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly preferably less than 0.1%.

Fe ₂ O ₃ The components function as clarifying agents, and the components are inevitably mixed as impurities. Fe (Fe) ₂ O ₃ The content of (C) is 0.001-0.05%, 0.003-0.03%, especially 0.005-0.019%. If Fe is ₂ O ₃ If the content of (2) is too small, a high-purity raw material is required, and the raw material cost tends to increase. On the other hand, if Fe ₂ O ₃ If the content of (b) is too large, the transmittance tends to be low.

As a material other than Fe ₂ O ₃ Other clarifying agent can be added with 0-2% of As ₂ O ₃ 、Sb ₂ O ₃ 、CeO ₂ 、SnO ₂ 、F、Cl、SO ₃ One or two or more of them. Wherein As from the environmental point of view ₂ O ₃ And F is preferably substantially free, i.e., less than 0.1%. In particular, when considering the clarifying ability and the influence of the environment, snO is preferable as the clarifying agent ₂ 。SnO ₂ The range of the lower limit is preferably 0% or more and 0.1% or more, particularly preferably 0.15% or more, and the range of the upper limit is preferably 1% or less, 0.5% or less, 0.4% or less, particularly preferably 0.3% or less. Sb (Sb) ₂ O ₃ The range of the lower limit is preferably 0% or more, 0.03% or more, 0.05% or more, particularly preferably 0.07% or more, and the range of the upper limit is preferably 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, particularly preferably 0.1% or less.

PbO and Bi ₂ O ₃ Is a component that reduces the high-temperature tackiness, and is preferably substantially free, i.e., less than 0.1%, from the viewpoint of the environment.

Y ₂ O ₃ 、La ₂ O ₃ 、Nb ₂ O ₅ 、Gd ₂ O ₃ 、Ta ₂ O ₅ 、WO ₃ Has the effect of improving Young's modulus. However, if the content of these components is more than 5%, in particular more than 1%, the raw material cost increases.

The glass of the present invention preferably has the following characteristics.

The softening point is 720 ℃ or less, preferably 715 ℃ or less, particularly preferably 600 to 700 ℃. If the softening point is too high, thermal degradation of the mold or the like is likely to occur during curved surface processing, and the glass sheet is shaped to conform to the shape of the mold, thereby making it difficult for the shape change to occur.

The average linear thermal expansion coefficient at a temperature range of 30 to 380℃is preferably 50X 10 ^-7 ～125×10 ^-7 /℃、65×10 ^-7 ～110×10 ^-7 /℃、80×10 ^-7 ～105×10 ^-7 /℃、85×10 ^-7 ～100×10 ^-7 Preferably 88X 10 at a temperature of °C ^-7 ～98×10 ^-7 and/C. If the average linear thermal expansion coefficient is outside the above range, it is difficult to match the thermal expansion coefficients of various surrounding members (particularly, functional films and the like), and cracking and breakage of the glass plate are likely to occur when the glass plate is assembled to the device. The "average linear thermal expansion coefficient at a temperature range of 30 to 380" means a value measured by an dilatometer.

The liquid phase temperature is preferably less than 850 ℃, 825 ℃, 800 ℃ or less, 780 ℃ or less, 760 ℃ or less, particularly preferably 750 ℃ or less. The viscosity at the liquidus temperature is preferably 10 ^4.6 dPa.s or more, 10 ^5.2 dPa.s or more, 10 ^5.5 dPa.s or more, 10 ^5.8 dPa.s or more, particularly preferably 10 ^6.0 dPa.s or more. In this way, a glass sheet can be easily formed by the downdraw method, particularly the overflow downdraw method, and thus a thin glass sheet can be easily produced. Furthermore, devitrification and crystallization of the glass are not easily generated during molding. As a result of this, the processing time,the manufacturing cost of the glass plate is easy to be reduced.

High temperature viscosity 10 ^2.5 The temperature at dPa.s is preferably 1500℃or lower, 1400℃or lower, 1350℃or lower, 1320℃or lower, particularly preferably 1300℃or lower. If the high temperature viscosity is 10 ^2.5 When the temperature at dPa.s becomes high, the meltability decreases and the production cost of the glass sheet increases. Here, "high temperature viscosity 10 ^2.5 The "temperature at dPa.s" can be measured by the platinum ball pulling method.

However, in the glass manufacturing process, in order to heat the molten glass, electrodes are inserted into the melting vessel to directly heat the molten glass by electric current, and a feeder, a forming device, or the like is heated to indirectly heat the molten glass by electric current. However, when the molten glass is electrically heated, if a potential difference occurs between different metal members contacting the molten glass, a circuit is formed through the molten glass, and bubbles may occur at the metal/molten glass interface corresponding to the positive electrode and the negative electrode.

Specifically, when a circuit is formed, the following reaction occurs, and bubbles are generated in a portion that becomes the positive electrode side.

Positive electrode side: o (O) ^2- →0.5O ₂ +2e ^-

Negative electrode side: 0.5O ₂ +2e ^- →O ^2-

According to faraday's law of electrolysis, the mass of a substance that changes at each electrode by electrolysis is proportional to the amount of electricity that flows (see equation 1 below).

[ mathematics 1]

m＝(Q·M)/(F·Z)

m: mass of the changed substance (g)

Q: flow electric quantity (C)

M: molar mass of substance (g/mol)

F: faraday constant (C/mol)

Z: number of electrons associated with change in 1 molecule of substance

Here, the electric quantity Q is represented by the product of the current I and the time t (refer to equation 2). In addition, according to ohm's law, voltage is expressed as a product of resistance and current (refer to equation 3).

[ math figure 2]

Q＝I·t

I: current (A)

t: time (seconds)

[ math 3]

E＝R·I

E: voltage (V)

R: resistor (omega)

I: current (A)

Resistivity ρ (Ω·cm) of glass for resistance R (Ω) and conductivity cell constant κ (cm) determined by measuring device ^-1 ) Is represented by the product of (refer to equation 4).

[ mathematics 4]

R＝ρ·κ

R: resistor (omega)

ρ: resistivity (Ω cm)

Kappa: constant of conductivity cell (cm) ^-1 )

According to equations 2 to 4, the relation between the electric quantity Q and the resistivity ρ is inversely proportional to the resistivity ρ as in equation 5. It can be seen that: the higher the resistivity ρ, the smaller the electric quantity Q becomes, and the mass of the changed substance m=the amount of bubbles decreases.

[ math 5]

Q＝(E·t)/(ρ·κ)

Further, since the viscosity of the molten glass at the time of molding is substantially constant regardless of the glass composition, the higher the resistivity at the same viscosity is, the smaller the amount of bubbles generated at the time of molding becomes.

Therefore, the resistivity of the molten glass is preferably high, and the measurement frequency is 1kHz and the high-temperature viscosity is 10 ^5.0 The resistivity Log ρ at dPa·s is preferably 0.5 Ω·cm or more, 0.6 Ω·cm or more, 0.7 Ω·cm or more, 0.8 Ω·cm or more, 0.9 Ω·cm or more, 1.0 Ω·cm or more, and particularly preferably 1.1 to 10 Ω·cm. If the measuring frequency is 1kHz and the high-temperature viscosity is 10 ^5.0 When the resistivity Log ρ at dPa·s is too low, bubbles are generated in the molten glass, so that bubble defects increase, and the glass manufacturing cost increases. Here, "measurement frequency 1kHz, high temperature viscosity 10 ^5.0 Electric power at dPa.sThe resistivity Log ρ "can be measured by a two-terminal method.

Measuring frequency 1kHz, high temperature viscosity 10 ^3.0 The resistivity Log ρ at dPa·s is preferably 0.1 Ω·cm or more, 0.2 Ω·cm or more, 0.3 Ω·cm or more, 0.4 Ω·cm or more, 0.5 Ω·cm or more, 0.6 Ω·cm or more, and particularly preferably 0.7 to 7 Ω·cm. If the measuring frequency is 1kHz and the high-temperature viscosity is 10 ^3.0 When the resistivity Log ρ at dPa·s is too low, bubbles are generated in the molten glass, so that bubble defects increase, and the glass manufacturing cost increases. Here, "measurement frequency 1kHz, high temperature viscosity 10 ^3.0 The resistivity Log ρ "at dPa·s can be measured by a two-terminal method.

The Young's modulus is preferably 65GPa or more, 68GPa or more, 70GPa or more, particularly preferably 72GPa or more. If the Young's modulus is too low, it is difficult to maintain the shape when the plate thickness is thin. Here, the "young's modulus" can be measured by a known resonance method.

The glass of the present invention is preferably formed by a downdraw process, particularly an overflow downdraw process. The overflow downdraw process is the following: the molten glass is overflowed from both sides of the heat-resistant launder-like structure, and the overflowed molten glass is joined to the lower top end of the launder-like structure and is extended downward to form a glass plate. In the overflow downdraw method, a surface to be a surface of a glass sheet is formed in a free surface state without contacting a launder-like refractory. Therefore, a glass plate having high surface smoothness can be easily produced.

As a method for forming the glass sheet, for example, a slot down-draw method, a redraw method, a float method, a roll-down method, or the like may be selected in addition to the overflow down-draw method.

As described above, since the glass of the present invention has a low softening point, it can be shaped to a mold or the like to appropriately perform curved surface processing. Accordingly, the glass plate of the present invention is preferably subjected to a curved surface treatment, and more preferably subjected to a curved surface treatment by heat treatment. When the curved surface is formed by curved surface processing, the radius of curvature of the curved surface is preferably 100 to 2000mm, and particularly preferably 200 to 1000mm. In this way, the structure can be easily applied to a head-mounted display member.

The glass of the present invention preferably has no compressive stress layer due to ion exchange formed on the surface. In this way, the manufacturing cost of the glass can be reduced.

The glass of the present invention preferably has a plate shape, and the plate thickness is preferably 3.0mm or less, 2.5mm or less, 2.0mm or less, 1.5mm or less, 1.0mm or less, and particularly preferably 0.9mm or less. The thinner the plate thickness, the easier the glass plate is made lighter, and the easier the curved surface processing is performed. On the other hand, if the plate thickness is too small, the strength of the glass plate itself decreases. Therefore, the thickness is preferably 0.1mm or more, 0.2mm or more, 0.3mm or more, 0.4mm or more, 0.5mm or more, 0.6mm or more, and particularly preferably more than 0.7mm.

In the glass of the present invention, the surface roughness Ra of at least one surface is preferably 0.1 to 5. Mu.m, particularly preferably 0.3 to 3. Mu.m. When the curved surface is formed by heat treatment using a die, the surface roughness Ra of the surface in contact with the die is preferably controlled to be 0.1 to 5 μm, particularly preferably 0.3 to 3 μm. In this way, the display image is not made unclear, and the efficiency of curved surface processing can be improved. When the surface roughness Ra of the surface in contact with the mold is large, if the surface is tempered (fire polishing), the surface roughness Ra can be reduced.

The glass of the present invention preferably has a plate shape, and has a functional film on at least one surface, and the functional film is any one of an antireflection film, an antifouling film, a reflection film, and a scratch-proof film.

As the antireflection film, a dielectric multilayer film in which, for example, a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively high refractive index are alternately laminated is preferable. This facilitates control of the reflectance at each wavelength. The antireflection film may be formed by, for example, sputtering, CVD, or the like. The reflectance of the antireflection film at each wavelength (particularly, at a wavelength of 400 to 700 nm) is, for example, preferably 1% or less, 0.5% or less, 0.3% or less, and particularly preferably 0.1% or less.

The stain-proofing film is preferably produced by coating a solution of a silane compound having a fluoroalkyl group or a fluoroalkyl ether group, which contains a fluorine-containing silane compound in a stain-proofing layer-forming composition. In particular, the fluorine-containing silane compound is preferably silazane or alkoxysilane. Among the above silane compounds having a fluoroalkyl group or a fluoroalkyl ether group, a silane compound in which a fluoroalkyl group in the silane compound is bonded to a Si atom in a proportion of 1 or less per 1 Si atom and the balance is a hydrolyzable group or a siloxane bonding group is preferable. The hydrolyzable group mentioned here is, for example, a group such as an alkoxy group, and is hydrolyzed to form a hydroxyl group, whereby the silane compound forms a polycondensate.

As the reflective film, a metal film of Al or the like is preferable. As the scratch-resistant film, siO is preferable ₂ 、Si ₃ N ₄ And the like.

As described above, the glass of the present invention is suitable as a head-mounted display member, and is preferably used as a sensor member (particularly, a sensor member for measuring a vehicle distance) or an optical component member mounted on a vehicle.

As a sensor member mounted on a vehicle, a photodiode for measuring a vehicle distance LiDAR (Light Detection and Ranging) and the like are exemplified. In general, in order to improve weather resistance and impact resistance from external impact, a photodiode is manufactured by mounting the photodiode on a package of resin, ceramic, metal, or the like, and then sealing the photodiode with a cover glass having as small a difference in thermal expansion from the package as possible.

In order to prevent noise from being generated by the incident light reflected by the photodiode and reflected again by the photodiode, the cover glass for this application may be formed with an antireflection film. Further, as a light source for measuring the vehicle distance, ultraviolet light, visible light, near infrared light, or the like can be used, and in recent years, near infrared light having little spectral influence of sunlight, particularly light in a 920 to 960nm band (for example, a center wavelength of 940 nm), is often used. In the future, there is a possibility that infrared light in the 900 to 1690nm band, which has less influence of sunlight, will be used. Therefore, the antireflection film for this use preferably reflects light having a wavelength of 900nm or more, and the reflectance of the antireflection film in a wavelength region of 900 to 1690nm (particularly, a wavelength of 940 nm) is preferably 1% or less, 0.5% or less, 0.3% or less, and particularly preferably 0.1% or less. The reflectance of the antireflection film may have a minimum value in a region having a wavelength of 900nm or more, and a wavelength region showing the minimum value is preferably consistent with the center wavelength of the light source.

Example 1

The present invention will be described below based on examples. The following examples are merely illustrative. The present invention is not limited at all to the following examples.

Tables 1 and 2 show examples (sample nos. 1 to 20) and comparative examples (sample nos. 21 and 22) of the present invention.

TABLE 1

Glass composition (mol%)	No.1	No.2	No.3	No.4	No.5	No.6	No.7	No.8	No.9	No.10	No.11
												SiO ₂	58.1	54.1	56.1	52.1	59.1	55.6	57.6	54.1	60.6	61.6	61.6
Al ₂ O ₃	7.0	7.0	7.0	7.0	7.0	7.0	7.0	7.0	7.0	7.0	7.0
												B ₂ O ₃	6.0	6.0	6.0	6.0	6.0	6.0	6.0	6.0	9.0	5.0	5.0
Li ₂ O	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
												Na ₂ O	20.5	20.5	20.5	20.5	19.5	19.0	19.0	18.5	17.0	17.0	17.0
K ₂ O	0.004	0.002	0.002	0.002	0.003	0.002	0.003	0.002	0.002	0.002	0.003
												MgO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
CaO	3.6	3.6	5.6	5.6	3.6	3.6	5.6	5.6	3.6	5.6	3.6
												SrO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
BaO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
												ZnO	4.7	8.7	4.7	8.7	4.7	8.7	4.7	8.7	2.7	3.7	5.7
ZrO ₂	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
												SnO ₂	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1
Fe ₂ O ₃	0.005	0.004	0.010	0.009	0.005	0.004	0.004	0.004	0.001	0.003	0.003
												Mg+Ca+Sr+Ba	3.6	3.6	5.6	5.6	3.6	3.6	5.6	5.6	3.6	5.6	3.6
(Na-Al)/Si	0.232	0.250	0.241	0.259	0.212	0.216	0.208	0.213	0.165	0.162	0.162
												Na/(Li+Na+K)	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000
Al/(Li+Na+K)	0.341	0.341	0.341	0.341	0.359	0.368	0.368	0.378	0.412	0.412	0.412
												Ca/(Mg+Ca+Sr+Ba+Zn)	0.432	0.291	0.542	0.390	0.432	0.291	0.542	0.390	0.569	0.601	0.385
zn/(Mg+Ca+Sr+Ba+Zn)	0.568	0.709	0.458	0.610	0.568	0.709	0.458	0.610	0.431	0.399	0.615
												α(×10 ^-7 /℃)	103	105	105	107	100	100	101	101	90	94	93
ρ(g/cm ³ )	2.597	2.668	2.614	2.687	2.592	2.661	2.607	2.678	2.536	2.571	2.587
												Ps(℃)	488	481	486	478	495	491	495	490	509	510	506
Ta(℃)	520	513	518	509	527	524	527	522	541	544	540
												Ts(℃)	662	650	655	644	671	665	669	661	685	697	694
10 ^4.0 dPa·s(℃)	893	869	875	853	913	896	902	883	931	965	968
												10 ^3.0 dPa·s(℃)	1037	1002	1011	979	1061	1035	1044	1016	1082	1126	1130
10 ^2.5 dPa·s(℃)	1139	1096	1107	1067	1166	1133	1145	1108	1190	1239	1244
												Logρ(Ω·cm)10 ^5.0 dPa·s	1.34	1.42	1.42	1.50	1.33	1.46	1.45	1.51	1.50	1.37	1.32
Logρ(Ω·cm)10 ^3.0 dPa·s	0.65	0.73	0.73	0.80	0.62	0.73	0.71	0.82	0.76	0.67	0.63
												TL(℃)	766	776	808	852	777	776	848	868	846	880	860
logη _TL	5.5	5.1	4.8	4.0	5.6	5.4	4.6	4.2	4.9	4.8	5.0
												Young's modulus (GPa)	74	73	74	74	74	74	75	75	75	75	74
Weather resistance	○	○	○	○	○	○	○	○	○	○	○

TABLE 2

Glass composition (mol%)	No.12	No.13	No.14	No.15	No.16	No.17	No.18	No.19	No.20	N0.21	No.22
												SiO ₂	58.6	56.6	52.6	59.6	55.5	53.7	57.5	57.9	68.8	65.9	66.2
Al ₂ O ₃	7.0	7.0	7.0	6.0	4.0	3.9	2.0	0.0	4.9	5.0	12.8
												B ₂ O ₃	9.0	9.0	9.0	6.0	13.8	13.9	13.8	13.6	0.0	0.0	6.3
Li ₂ O	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
												Na ₂ O	17.0	17.0	17.0	17.0	20.5	20.5	20.6	20.4	20.6	5.0	0.0
K ₂ O	0.000	0.002	0.002	0.002	0.000	0.002	0.002	0.002	0.002	5.300	0.000
												MgO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	3.4	4.2
CaO	3.6	3.6	5.6	3.6	3.5	3.6	3.5	3.5	3.6	2.7	7.6
												SrO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	6.1	0.3
BaO	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	4.0	2.5
												ZnO	4.7	6.7	8.7	7.7	2.6	4.4	2.6	4.5	1.9	0.0	0.0
ZrO ₂	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	2.7	0.0
												SnO ₂	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1
Fe ₂ O ₃	0.002	0.003	0.003	0.003	0.002	0.003	0.003	0.003	0.003	0.010	0.010
												Mg+Ca+Sr+Ba	3.6	3.6	5.6	3.6	3.5	3.6	3.5	3.5	3.6	16.1	14.6
(Na-Al)/Si	0.171	0.177	0.190	0.185	0.299	0.308	0.324	0.353	0.228	0.000	-0.19
												Na/(Li+Na+K)	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	0.483	0.000
Al/(Li+Na+K)	0.412	0.412	0.412	0.353	0.192	0.191	0.096	0.000	0.240	0.485	0.000
												Ca/(Mg+Ca+Sr+Ba+Zn)	0.432	0.348	0.390	0.317	0.577	0.446	0.577	0.437	0.650	0.166	0.519
Zn/(Mg+Ca+Sr+Ba+Zn)	0.568	0.652	0.610	0.683	0.423	0.554	0.423	0.563	0.350	0.000	0.000
												a(×10 ^-7 /℃)	91	92	95	94	101	103	101	104	106	85	37
ρ(g/cm ³ )	2.570	2.604	2.652	2.629	2.571	2.603	2.581	2.625	2.515	2.820	2.520
												Ps(℃)	504	499	494	499	495	489	498	496	473	582	687
Ta(℃)	536	531	525	533	525	519	528	525	512	628	743
												Ts(℃)	678	671	659	679	647	639	649	645	691	837	977
10 ^4.0 dPa·s(℃)	917	899	864	918	815	803	813	805	1000	1150	1285
												10 ^3.0 dPa·s(℃)	1062	1036	987	1061	914	900	909	894	1182	1311	1440
10 ^2.5 dPa·s(℃)	1169	1135	1075	1163	987	970	979	959	1305	1411	1540
												Logρ(Ω·cm)10 ^5.0 dPa·s	1.46	1.51	1.63	1.43	1.52	1.57	1.53	1.56	1.00	2.45	4.35
Logρ(Ω·cm)10 ^3.0 dPa·s	0.75	0.81	0.93	0.75	0.94	0.97	0.93	0.96	0.33	1.10	2.62
												TL(℃)	827	804	829	835	708	693 or less	681 or less	693 or less	745	1010	1123
logη _TL	5.0	5.1	4.4	4.9	5.9	5.9 or more	6.6 or more	6.2 or more	6.7	5.2	5.6
												Young's modulus (GPa)	74	74	75	74	77	76	78	78	69	77	78
Weather resistance	○	○	○	○	○	○	○	○	○	○	○

First, a glass batch obtained by blending glass raw materials so as to achieve the glass composition shown in the table was put into a platinum crucible and melted at 1200 to 1500 ℃ for 4 hours. During melting of the glass batch, the glass batch was homogenized by stirring with a platinum stirrer. Then, the obtained molten glass was poured onto a carbon plate, formed into a plate shape, and then cooled slowly from a temperature about 20 ℃ higher than the annealing point Ta to room temperature at a rate of 3 ℃/min. For each sample obtained, the average linear thermal expansion coefficient α, density ρ, strain point Ps, annealing point Ta, softening point Ts, and high temperature viscosity 10 were evaluated at a temperature range of 30 to 380 ℃ ^4.0 Temperature at dPa.s, high temperature viscosity 10 ^3.0 Temperature at dPa.s, high temperature viscosity 10 ^2.5 Temperature at dPa.s, measurement frequency of 1kHz and high temperature viscosity of 10 ^5.0 Resistivity Log ρ at dPa.s, measurement frequency 1kHz and high temperature viscosity 10 ^3.0 Resistivity Log ρ at dPa.s, liquidus temperature TL, viscosity η at liquidus temperature TL, and weatherability.

The average linear thermal expansion coefficient α at a temperature range of 30 to 380 ℃ is a value measured by an dilatometer.

The density ρ is a value measured by a known archimedes method.

The strain point Ps, the annealing point Ta, and the softening point Ts are values measured based on the method of ASTM C336 or ASTM C338.

High temperature viscosity 10 ^4.0 dPa·s、10 ^3.0 dPa·s、10 ^2.5 The temperature at dPa.s is a value measured by a platinum ball pulling method.

Measuring frequency 1kHz, high temperature viscosity 10 ^5.0 Resistivity Log ρ at dPa.s and measurement frequency 1kHz, high temperature viscosity 10 ^3.0 The resistivity Log ρ at dpa·s is a value measured by the two-terminal method.

The liquidus temperature TL is a value measured as follows: glass powder passing through a standard sieve of 30 mesh (500 μm) and remaining in a 50 mesh (300 μm) was charged into a platinum boat, and the mixture was kept in a temperature gradient furnace for 24 hours, and then the temperature at which crystals precipitated was measured by microscopic observation. The viscosity η at the liquidus temperature TL is a value obtained by measuring the glass viscosity at the liquidus temperature TL by the platinum ball pulling method.

Young's modulus is a value measured by a known resonance method.

Weather resistance was evaluated using the HAST test. Specifically, after each sample was kept at 121 ℃ and a humidity of 95% and at 2 atmospheres for 24 hours, the glass surface was evaluated as "o" when no peeling and cracking occurred, and as "x" when peeling and/or cracking occurred.

From the table it can be stated that: the softening point Ts of the samples No.1 to 20 was 697℃or lower and the viscosity eta at the liquid phase temperature TL was 10 ^4.0 dPa.s or more, and good weather resistance. Thus, the samples Nos. 1 to 20 were excellent in curved surface workability, devitrification resistance and weather resistance. On the other hand, the softening points Ts of sample nos. 21 and 22 were 837 ℃ and 977 ℃, respectively, and it was considered that it was difficult to perform the curved surface processing.

Example 2

The glasses (plate thickness: 0.8 mm) described in sample nos. 1 to 20 were curved at a temperature near the softening point Ts in order to shape the glasses to a mold, and then a concave mirror was produced by forming a reflective film of Al on the concave side surface to reflect the light.

On the other hand, in the glasses (plate thickness of 0.8 mm) of sample nos. 21 and 22, the curved surface processing was performed at a temperature in the vicinity of the softening point Ts in order to shape the glass to the mold, but the temperature at the time of the curved surface processing was high, and therefore thermal degradation was confirmed in the mold.

Industrial applicability

The glass of the present invention is excellent in curved surface workability, devitrification resistance and weather resistance, and is therefore suitable for a head-mounted display member, and is also excellent in devitrification resistance and weather resistance, and is therefore also suitable for a cover glass for a CCD or CMOS imaging element, a cover glass for a photodiode for vehicle distance measurement LiDAR (Light Detection and Ranging), and the like, and is excellent in curved surface workability (hot workability) and weather resistance, and is therefore also suitable for a medical tube glass.

Claims

1. A glass for curved surface processing, characterized by comprising SiO in mole% as a glass composition ₂ 40％～70％、Al ₂ O ₃ 3％～20％、B ₂ O ₃ 0％～15％、Li ₂ O 0％～15％、Na ₂ O8.6％～25％、K ₂ 0 to 1 percent of O, 2 to 10 percent of CaO and 1.5 to 15 percent of ZnO, wherein ZnO/(MgO+CaO+SrO+BaO+ZnO) is 0.2 to 1.0, and the softening point of the glass is more than 600 ℃ and less than 685 ℃.

2. The glass for curved surface processing according to claim 1, wherein SiO is contained in mol% as the glass composition ₂ 40％～70％、Al ₂ O ₃ 4.4％～20％、B ₂ O ₃ 0.1％～13.6％、Li ₂ O 0％～15％、Na ₂ O 13％～25％、K ₂ 0-1% of O, 2-10% of CaO, 0-2% of SrO, 0-2% of BaO and 2-15% of ZnO, and the softening point of the glass is 600-685 ℃.

3. The glass for curved surface processing according to claim 1 or 2, wherein the glass is plate-shaped.

4. The glass for curved surface processing according to claim 1 or 2, wherein the surface roughness Ra of at least one surface is 0.1 μm to 5 μm.

5. The glass for curved surface processing according to claim 3, wherein the thickness of the glass is 0.1mm to 3mm.

6. The glass for curved surface processing according to claim 3, wherein at least one surface has a functional film, and the functional film is any one of an antireflection film, an antifouling film, a reflecting film, and a scratch-proof film.

7. The glass for curved surface processing according to claim 3, wherein the glass is formed by an overflow downdraw method.

8. The curved surface according to claim 1 or 2A process glass having a viscosity of 10 at a liquidus temperature ^4.6 dPa.s or more.

9. The glass for curved surface processing according to claim 1 or 2, wherein the glass is used as a head-mounted display member.

10. The glass for curved surface processing according to claim 1 or 2, wherein the glass is used for a sensor member or an optical component member mounted on a vehicle.

11. The glass for curved surface processing according to claim 10, wherein the glass is used as a sensor member for measuring a vehicle distance.