CN116710412A

CN116710412A - Fluorophosphate glass and near infrared cut-off filter

Info

Publication number: CN116710412A
Application number: CN202180087320.3A
Authority: CN
Inventors: 大口佳奈子; 坂上贵寻
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2020-12-25
Filing date: 2021-12-13
Publication date: 2023-09-05
Also published as: JPWO2022138299A1; TW202231594A; WO2022138299A1

Abstract

The application relates to a fluorophosphate glass which contains P, F, O as an essential component and Cu in cation% ²⁺ 5 to 14 percent (Ca) ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ (ΣR ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ The total amount of (C) is 0.75 to 1.0, li ⁺ Content of (C/sigma R ')' ⁺ (ΣR’ ⁺ Refers to Li ⁺ 、Na ⁺ The total amount of (2) is 0.75 to 1.0 (excluding 1.0), and the Young's modulus is 70GPa or more.

Description

Fluorophosphate glass and near infrared cut-off filter

Technical Field

The present application relates to a fluorophosphate glass used for a color correction filter of a digital camera, a color video camera, or the like, and a near infrared cut filter produced using the same.

Background

Solid imaging elements such as CCDs and CMOS used in digital cameras have spectral sensitivity ranging from the visible light range to the near infrared range around 1200 nm. Therefore, since good color reproducibility cannot be obtained when used as it is, the visual acuity is corrected using near infrared cut filter glass to which a specific substance that absorbs infrared rays is added. In order to make the near infrared cut filter glass selectively absorb the wavelength in the near infrared region and have high weather resistance, an optical glass obtained by adding a copper component to a fluorophosphate glass has been developed and used. As these glasses, the composition thereof is disclosed in patent document 1.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2006-182586

Disclosure of Invention

Technical problem to be solved by the application

Cameras and the like using solid imaging elements are becoming thinner and thinner. At the same time, the imaging device and its peripheral components are required to be thin. In the case of forming a near infrared cut filter glass into a sheet by adding a copper component to a fluorophosphate glass, it is known that, for example, a magnesium component can be added to increase the hardness of the glass (see patent document 1). However, when these components are added, devitrification may occur during glass molding.

The purpose of the present application is to provide a fluorophosphate glass which has high strength and is advantageous for thinning, and which is suppressed in devitrification, and a near infrared cut filter produced using the fluorophosphate glass.

Technical proposal adopted for solving the technical problems

The present inventors have conducted intensive studies and found that, when the content ratio of an alkali metal component and an alkaline earth metal component is within a predetermined range for a fluorophosphate glass, a glass having high strength and less tendency to devitrification can be obtained and further desired optical characteristics can be obtained.

The fluorophosphate glass according to an embodiment of the present application is characterized by comprising P, F, O as an essential component and Cu in cation% ²⁺ 5 to 14 percent (Ca) ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ (ΣR ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ The total amount of (C) is 0.75 to 1.0, li ⁺ Content of (C/sigma R ')' ⁺ (ΣR’ ⁺ Refers to Li ⁺ 、Na ⁺ The total amount of (2) is 0.75 to 1.0 (excluding 1.0), and the Young's modulus is 70GPa or more.

Effects of the application

According to one embodiment of the present application, it is possible to obtain a fluorophosphate glass having desired optical characteristics that is less likely to cause devitrification and thus enables low-temperature melting of a glass raw material, and a near infrared cut filter produced using the same. Further, according to the present application, since the strength of the glass is high, the risk of occurrence of cracks during thinning can be reduced.

Drawings

Fig. 1 shows transmittance in examples of the present application and comparative examples.

Detailed Description

The fluorophosphate glass according to an embodiment of the present application (hereinafter, also simply referred to as "glass") contains P, F, O as an essential component, and Cu in cation% ²⁺ 5 to 14 percent (Ca) ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ (ΣR ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ The total amount of (C) is 0.75 to 1.0, li ⁺ Content of (C/sigma R ')' ⁺ (ΣR’ ⁺ Refers to Li ⁺ 、Na ⁺ The total amount of (2) is 0.75 to 1.0 (excluding 1.0), and the Young's modulus is 70GPa or more.

In the present specification, "cation%" and "anion%" refer to units as follows. First, the constituent components of the glass are divided into a cationic component and an anionic component. "cation%" means a unit expressed in terms of mole percent of the content of each cationic component, with the total content of all cationic components contained in the glass being 100 mole percent. "anion%" means a unit expressed in mole percent of the content of each anion component, based on 100 mole percent of the total content of all anion components contained in the glass. In the following description, unless otherwise specified, the content "%" of the component-containing component of the glass of the present application is cation% for the cation component and anion% for the anion component.

The glass of the present embodiment is copper-containing fluorophosphate glass containing P, F, O as an essential component. The glass containing P as the main component has an effect of improving the near infrared cut-off property. In addition, the inclusion of F in the glass can improve weatherability.

The glass of the present embodiment contains 5 to 14% of Cu which is a component imparting near infrared ray cut-off property and improving weather resistance ²⁺ . In addition, due to Cu ²⁺ The glass has a characteristic that phosphate chains in the glass are drawn together to form a crosslinked structure, so that the glass structure is reinforced and the Young's modulus is improved. If Cu is ²⁺ If the content is less than 5%, the near infrared absorption may be lowered when the glass is thinned. Cu (Cu) ²⁺ Preferably 6% or more, more preferably 8% or more. In addition, if Cu ²⁺ Above 14%, the glass becomes unstable and the risk of devitrification increases. Cu (Cu) ²⁺ Preferably 12% or less, more preferably 10% or less.

In the glass of the present embodiment, the cation percentage (Ca ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ (ΣR ²⁺ Refers to Ba ² ⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ The total amount of (2) is 0.75 to 1.0.

Containing R ²⁺ (R ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ ) Has the effects of stabilizing glass, improving Young's modulus and improving weather resistance. Specifically, due to R ²⁺ The glass has a characteristic that phosphate chains in the glass are drawn together to form a crosslinked structure, so that the glass structure is reinforced and the Young's modulus is improved. Preferably contains 1 to 20% of Sigma R ²⁺ . If ΣR ²⁺ When the content is 1% or more, the effect of stabilizing the glass can be sufficiently obtained. ΣR ²⁺ Preferably at least 3%, more preferablySelecting more than 5%. In addition, if ΣR ²⁺ When the content is 20% or less, deterioration of devitrification and the like can be sufficiently suppressed. ΣR ²⁺ Preferably 15% or less, more preferably 10% or less.

The present inventors have conducted a process comprising ²⁺ 、Sr ²⁺ 、Ca ²⁺ The glass of (2) was subjected to a melting property test and analyzed for impurities confirmed in the glass, whereby crystals containing P, O, cu, ba, sr, ca were detected. Furthermore, 3 glasses having only Ba reduction, only Sr reduction, and only Ca reduction were prepared from the glass from which the above crystal was detected, and the melting property test was performed, so that it was confirmed that the glass having only Sr reduction was excellent in melting property, and Sr was reduced ²⁺ Is effective for improving the melting property.

Furthermore, the present inventors implemented a method comprising Ba ²⁺ 、Ca ²⁺ 、Mg ²⁺ Glass of (2) and the glass contains only Mg ²⁺ (the content ratio of other components was the same). As a result, it contains Mg ²⁺ Is poor in glass-melting property and contains no Mg alone ²⁺ The glass of (2) has good melting property. Thereby, it was confirmed that Mg was reduced ²⁺ Is effective for improving the melting property.

From the above results, it was found that Σr was reduced in order to improve the glass meltability ²⁺ Middle Sr ²⁺ And Mg (magnesium) ²⁺ The content of (c) is advantageous for suppressing the risk of devitrification of the glass.

If (Ca) ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ (ΣR ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ The total amount of (c) is less than 0.75), the risk of devitrification may increase. (Ca) ²⁺ Content of +Ba ²⁺ Content of/(Σr) ²⁺ Preferably 0.8 or more, more preferably 0.86 or more, still more preferably 0.95 or more, still more preferably 1.0.

In the glass of the present embodiment, li in cation% ⁺ Content of (C/sigma R ')' ⁺ (ΣR’ ⁺ Refers to Li ⁺ 、Na ⁺ The total amount of (2) is 0.75 to 1.0 (excluding 1.0).

Li ⁺ 、Na ⁺ Ion diffusion coefficient ratio of (2)The other components are large, but when the two components are combined and contained in the glass, the mixed alkali effect causes the characteristic of having smaller ion diffusion coefficients than the respective components. Specifically, due to Li ⁺ 、Na ⁺ The respective ion radii are different, so that the respective ions are less likely to move when mixed in the glass than when they are present in the glass alone. That is, the mobility of each ion decreases, and thus the ion diffusion coefficient decreases. In particular, li ⁺ Relative to ΣR' ⁺ The higher the content ratio of (c), the more stable the glass, and the less likely the structure relaxation occurs, and thus the young's modulus increases.

If Li ⁺ Content of (C/sigma R ')' ⁺ (ΣR’ ⁺ Refers to Li ⁺ 、Na ⁺ The total amount of (2) is less than 0.75, the Young's modulus may be decreased. Li (Li) ⁺ Content of (C/sigma R ')' ⁺ Preferably 0.78 or more, more preferably 0.8 or more. In addition, if Li ⁺ Content of (C/sigma R ')' ⁺ If the Young's modulus is 1.0, there is a concern that Young's modulus may be lowered. Li (Li) ⁺ Content of (C/sigma R ')' ⁺ Preferably 0.95 or less, more preferably 0.9 or less.

ΣR’ ⁺ The content of the component (A) is preferably 20 to 50% because of the effects of stabilizing the glass and lowering the melting temperature of the glass. If ΣR' ⁺ When the content is 20% or more, the effect can be sufficiently obtained. ΣR' ⁺ Preferably 25% or more, more preferably 30% or more. In addition, if ΣR' ⁺ When the content is 50% or less, the decrease in devitrification and the like can be sufficiently suppressed. ΣR' ⁺ Preferably 45% or less, more preferably 40% or less.

The reason why the content (expressed as cation% and anion%) of each component constituting the glass according to the present embodiment is limited will be described below.

(cationic component)

P ⁵⁺ Is a main component for forming glass (glass forming oxide), and is an essential component for improving the stability of glass. P (P) ⁵⁺ The content of (2) is preferably 30 to 60%. If P ⁵⁺ When the content is 30% or more, the effect can be sufficiently obtained, whereas when it is 60% or less, the glass can be sufficiently prevented from becoming unstable, and the glass can be sufficiently prevented from being deformedAnd a decrease in weather resistance. P (P) ⁵⁺ The content of (2) is more preferably 40 to 60%, still more preferably 40 to 50%.

Al ³⁺ The glass-forming main component (glass-forming oxide) may be a component that combines with non-crosslinked oxygen in glass to form a dense glass network to improve young's modulus, weather resistance, and chemical durability. Al (Al) ³⁺ The content of (2) is preferably 4 to 20%. If Al is ³⁺ When the content of (2) is 4% or more, the effect can be sufficiently obtained, whereas when it is 20% or less, the risk of devitrification can be sufficiently reduced. Al (Al) ³⁺ The content of (2) is more preferably 6 to 15%, still more preferably 6 to 12%.

Li ⁺ Is a component for stabilizing glass and improving Young's modulus. In the presence of Li ⁺ In the case of (1), li ⁺ The content of (2) is preferably 15 to 40%. If Li ⁺ If the content is 15% or more, the effect can be sufficiently obtained, whereas if it is 40% or less, the glass can be sufficiently prevented from becoming unstable. Li (Li) ⁺ The content of (2) is more preferably 20 to 40%.

Na ⁺ Is a component for stabilizing glass. In the presence of Na ⁺ In the case of (1), na ⁺ The content of (2) is preferably 0.1 to 15%. If Na is ⁺ When the content is 0.1% or more, the effect can be sufficiently obtained, whereas when it is 15% or less, the decrease in Young's modulus can be sufficiently suppressed. Na (Na) ⁺ The content of (2) is preferably 0.1 to 10%, more preferably 0.1 to 6%.

K ⁺ The component (b) is not essential, but is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, and the like. However, in the presence of K ⁺ In the case of (2), the strength may be lowered, and thus is preferably not contained.

Ca ²⁺ Is a component for improving Young's modulus, weather resistance and stabilizing glass. In the presence of Ca ²⁺ In the case of (1), ca ²⁺ The upper limit of the content of (2) is preferably 10% or less. If Ca is ²⁺ When the content of (2) is 10% or less, the glass becomes sufficiently inhibited from becoming unstable, and the deterioration of devitrification can be sufficiently inhibited. Ca (Ca) ²⁺ The content of (2) is more preferably 0 to 6%.

Ba ²⁺ Is a component for improving Young's modulus, weather resistance and stabilizing glass. In the presence of Ba ²⁺ In the case of Ba ²⁺ The upper limit of the content of (2) is preferably 10% or less. If Ba is ²⁺ When the content of (2) is 10% or less, the glass becomes sufficiently inhibited from becoming unstable, and the deterioration of devitrification can be sufficiently inhibited. Ba (Ba) ²⁺ The content of (2) is more preferably 0 to 6%.

Sr ²⁺ The glass is not essential, but is a component for improving Young's modulus and weather resistance of the glass. In the presence of Sr ²⁺ In the case of Sr ²⁺ The upper limit of the content of (2) is preferably 5% or less. If Sr ²⁺ When the content of (2) is 5% or less, the glass becomes sufficiently inhibited from becoming unstable, and the deterioration of devitrification can be sufficiently inhibited. Sr (Sr) ²⁺ The content of (2) is more preferably 0 to 2%, and even more preferably no.

Mg ²⁺ The glass is not essential, but is a component for improving Young's modulus and weather resistance of the glass. In the presence of Mg ²⁺ In the case of (1), mg ²⁺ The upper limit of the content of (2) is preferably 5% or less. If Mg is ²⁺ When the content of (2) is 5% or less, the glass becomes sufficiently inhibited from becoming unstable, and the deterioration of devitrification can be sufficiently inhibited. Mg of ²⁺ The content of (2) is more preferably 0 to 2%, and even more preferably no.

Zn ²⁺ The glass is not essential, but is a component for improving Young's modulus and weather resistance of the glass. In the presence of Zn ²⁺ In the case of (2), zn ²⁺ The upper limit of the content of (2) is preferably 10% or less. If Zn ²⁺ When the content of (2) is 10% or less, the glass becomes sufficiently inhibited from becoming unstable, and the deterioration of devitrification can be sufficiently inhibited. Zn (zinc) ²⁺ The content of (2) is more preferably 0 to 5%, still more preferably 0 to 2%.

The glass of the present embodiment may contain 0 to 1% of Sb as an optional cation component ³⁺ 。Sb ³⁺ Not essential components, but has the effect of improving the transmittance in the visible light region. In the presence of Sb ³⁺ If the content is 1% or less, the decrease in the stability of the glass can be sufficiently suppressed. Sb (Sb) ³⁺ The content of (2) is preferably 0.01 to 0.8%,more preferably 0.05 to 0.5%, still more preferably 0.1 to 0.3%.

The glass of the present embodiment may further contain other components that are generally contained in fluorophosphate glasses such as S, si, B, etc., as optional cation components, within a range that does not impair the effects of the present application. The total content of these components is preferably 5% or less.

(anionic component)

O ^2- The content of the essential component for stabilizing the glass, improving the transmittance in the visible light range, improving the mechanical properties such as strength, hardness and elastic modulus, and reducing the ultraviolet transmittance is preferably 40 to 95%. If O ^2- When the content of (2) is 40% or more, the effect can be sufficiently obtained, whereas when it is 95% or less, the glass becomes sufficiently unstable and the decrease in weather resistance can be sufficiently suppressed.

To improve Young's modulus of glass, O ^2- The content of (2) is preferably 80 to 95% (but not 80%). In this case, O ^2- The content of (2) is more preferably 82 to 93%, still more preferably 85 to 92%.

O for improving weather resistance of glass ^2- The content of (2) is preferably 40 to 80%. In this case, O ^2- The content of (2) is more preferably 50 to 70%, still more preferably 50 to 60%.

F ^- Essential components for stabilizing glass. F (F) ^- The content of (2) is preferably 5 to 60%. If F ^- When the content of (2) is 5% or more, the occurrence of unmelted product during melting of the glass raw material can be sufficiently suppressed. If F ^- When the content of (C) is 60% or less, the increase in volatility and the increase in the glass fiber cord can be sufficiently suppressed.

F for improving Young's modulus of glass ^- The content of (2) is preferably 5 to 20% (but 20% is not included). In this case F ^- The content of (2) is more preferably 7 to 18%, still more preferably 8 to 15%.

F for improving weather resistance of glass ^- The content of (2) is preferably 20 to 60%. In this case F ^- The content of (2) is more preferably 30 to 50%, still more preferably 40 to 50%.

The glass of the present embodiment may further contain other components generally contained in fluorophosphate glass such as Cl, br, I, etc., as optional anion components, within a range that does not impair the effects of the present application. The total content of these components is preferably 5% or less.

Next, the content of any component other than the above components in the present embodiment will be described. In the present specification, "substantially free" means that the material is not intended to be used as a raw material, and unavoidable impurities mixed from raw material components or production steps are regarded as being free.

The glass of the present embodiment preferably contains substantially no PbO and As ₂ O ₃ 、V ₂ O ₅ 、YbF ₃ And GdF ₃ Any one of the above. PbO is a component that reduces the viscosity of glass and improves the manufacturing workability. And As ₂ O ₃ Is a component functioning as an excellent clarifier capable of generating a clarified gas in a wide temperature range. However, pbO and As ₂ O ₃ Is an environmental load substance, and therefore is preferably as free as possible. V (V) ₂ O ₅ Since the glass absorbs light in the visible light range, it is preferable that the glass does not contain near infrared cut filter glass for solid imaging elements, which has a high requirement for transmittance in the visible light range. YbF ₃ 、GdF ₃ Although the glass is a component for stabilizing glass, the raw materials thereof are relatively expensive and cause an increase in cost, and therefore, it is preferable to be as free of the glass as possible.

The term "substantially free" as used herein means that the components are not intended to be used as raw materials, and that the content of each component in the near infrared cut filter glass is 0.1% or less.

Nitrate compounds or sulfate compounds having glass-forming cations may be added to the glass of the present embodiment as oxidizing agents or fining agents. The oxidizing agent has Cu in the total Cu content in the glass by increasing the Cu content ²⁺ The ratio of ions improves the transmittance in the visible region and the near infrared ray cut-off.

In the case of containing a nitrate compound or a sulfate compound, the addition amount thereof is preferably 0.5 to 15% by mass in terms of an additional addition amount with respect to the raw material mixture. When the amount of the nitrate compound or the sulfate compound is 0.5 mass% or more, the effect of improving the transmittance is easily exhibited, whereas when it is 15 mass% or less, the difficulty in forming glass can be sufficiently suppressed. The amount of the nitrate compound or sulfate compound added is more preferably 1 to 10% by mass, and still more preferably 3 to 8% by mass.

As the nitrate compound, al (NO) ₃ ) ₃ 、LiNO ₃ 、NaNO ₃ 、KNO ₃ 、Ca(NO ₃ ) ₂ 、Sr(NO ₃ ) ₂ 、Ba(NO ₃ ) ₂ 、Zn(NO ₃ ) ₂ 、Cu(NO ₃ ) ₂ Etc. As the sulfate compound, it is Al ₂ (SO ₄ ) ₃ ·16H ₂ O、Li ₂ SO ₄ 、Na ₂ SO ₄ 、K ₂ SO ₄ 、CaSO ₄ 、SrSO ₄ 、BaSO ₄ 、ZnSO ₄ 、CuSO ₄ Etc.

The Young's modulus of the glass of the present embodiment is required to be 70GPa or more. Fracture toughness (K) of glass _1C ) The fracture energy (r) and Young's modulus (E) are in a functional relation shown in the following formula. Therefore, it is effective to improve the Young's modulus of glass for improving the strength of glass.

[ math 1]

K _1C ＝(2rE) ^1/2

If the Young's modulus is less than 70GPa, the glass sheet is likely to crack or be damaged in the polishing step, and if the glass is used in an imaging device or the like, the glass may be broken. Preferably 75GPa or more.

In the glass of the present embodiment, the average transmittance of light having a wavelength of 450 to 600nm is preferably 80% or more when the thickness is 0.1 mm. When the average transmittance is 80% or more, light in the visible light range can be sufficiently transmitted, and a clear image can be displayed when the device is used for imaging.

In addition, the glass of the present embodiment preferably has a transmittance of 50% in the range of 600 to 670nm at a plate thickness of 0.1 mm. If such conditions are satisfied, a thin sensor is required to achieve desired optical characteristics. When the plate thickness is 0.1mm, the near infrared cut filter is a thin plate and has excellent optical characteristics when the transmittance of light having a wavelength of 400nm is 85% or more and the transmittance of light having a wavelength of 1200nm is 40% or less.

The transmittance value was converted into a value of 0.1mm in thickness. The transmittance was converted by the following formula 1. T (T) _i1 Means that the internal transmittance (data after removing reflection loss from the front and back surfaces) of the sample is measured, t ₁ Means that the thickness (for example, 0.15 to 0.3 mm) of the sample is measured, T _i2 The transmittance of the converted value, t ₂ The plate thickness (0.1 mm in the case of the present application) is calculated.

[ formula 2]

Since the near infrared cut filter glass of the present embodiment can cope with downsizing and thinning of imaging equipment and peripheral components thereof, good spectroscopic characteristics can be obtained even in a state where the glass has a small plate thickness. The thickness of the glass is preferably 0.5mm or less, more preferably 0.3mm or less, further preferably 0.2mm or less, and most preferably 0.15mm or less. The lower limit of the thickness of the glass is not particularly limited, but is preferably 0.03mm or more, more preferably 0.05mm or more, in view of the strength of the glass that is not easily broken during the manufacture of the glass or during the transportation of the glass when mounted on an imaging device.

The glass of the present embodiment may be formed into a near infrared cut filter by forming an optical multilayer film on at least one surface of the glass after forming the glass into a predetermined shape. Examples of the optical multilayer film include an IR cut film (film reflecting near infrared rays), a UV/IR cut film (film reflecting ultraviolet rays and near infrared rays), a UV cut film (film reflecting ultraviolet rays), and an antireflection film. These optical films can be formed by a known method such as vapor deposition or sputtering.

An adhesion strengthening film may be provided between the glass and the optical multilayer film. By providing the adhesion enhancing film, adhesion between the glass and the optical multilayer film can be improved, and peeling of the film can be suppressed. Examples of the adhesion enhancing film include silicon oxide (SiO ₂ ) Titanium oxide (TiO) ₂ ) Lanthanum titanate (La) ₂ Ti ₂ O ₇ ) Alumina (Al) ₂ O ₃ ) Alumina and zirconia (ZrO ₂ ) Magnesium fluoride (MgF) ₂ ) Calcium fluoride (CaF) ₂ ) Strontium fluoride (SrF) ₂ ) Silicon fluoride, and the like. The substance containing fluorine or oxygen is preferable as the adhesion-enhancing film because the adhesion is higher, and in particular, the adhesion between magnesium fluoride and/or titanium oxide and glass or film is improved. The adhesion enhancing film may be a single layer or 2 or more layers. In the case of 2 layers or more, a plurality of substances may be combined.

The near infrared cut filter glass of the present embodiment can be prepared as follows. The raw materials are weighed and mixed so as to be within the above-mentioned composition range (mixing step). The raw material mixture is stored in a platinum crucible and melted by heating in an electric furnace at a temperature of 700 to 900 ℃. After sufficiently stirring and clarifying, the mixture is poured into a mold, and is cut and polished to form a flat plate having a predetermined thickness (forming step).

In the melting step of the above production method, the highest temperature of the glass in glass melting is preferably 900 ℃ or lower. This is because, when the highest temperature of the glass in melting of the glass exceeds the above temperature, transmittance characteristics deteriorate, and diffusion of fluorine is promoted, so that the glass becomes unstable. The above temperature is more preferably 880 ℃ or lower, still more preferably 850 ℃ or lower, still more preferably 820 ℃ or lower.

In addition, if the temperature in the melting step is too low, problems such as devitrification during melting and time taken for melting occur, and therefore, it is preferably 750 ℃ or higher, more preferably 800 ℃ or higher.

Examples

Examples and comparative examples of the present application are shown in tables 1 to 3. Examples 1 to 10 and examples 20 to 22 are examples of the present application, and examples 11 to 19 are comparative examples of the present application.

[ preparation of glass ]

The glass was weighed and mixed so that the glass components had the compositions (cation and anion%) shown in tables 1 to 3, placed in a platinum crucible having an internal volume of about 1L, melted at a temperature of 800 to 900℃for 2 hours, clarified, stirred, poured into a rectangular mold having a length of 100 mm. Times. Width of 80 mm. Times. Height of 20mm and preheated to about 50 to 500℃and then cooled slowly to 360 to 440℃and cooled at about 1℃per minute, to obtain a sample. Next, the front and back surfaces were optically polished to obtain glass having a thickness of 0.15 to 0.3 mm.

The raw materials of each glass were each P ⁵⁺ In the case of (1) is selected from H ₃ PO ₄ And Al (PO) ₃ ) ₃ 1 of (1), al ³⁺ In the case of (a) is selected from AlF ₃ 、Al(PO ₃ ) ₃ And Al ₂ O ₃ 1 of (1), li ⁺ In the case of (B) is selected from LiF and LiNO ₃ 、Li ₂ CO ₃ And LiPO ₃ 1 of (1), sr ²⁺ In the case of (a) is selected from SrF ₂ 、SrCO ₃ And Sr (PO) ₃ ) ₂ 1 of (1), ba ²⁺ In the case of (a) is selected from BaF ₂ 、BaCO ₃ And Ba (PO) ₃ ) ₂ 1 of (1), na ⁺ Is selected from NaCl, naBr, naI, naF and Na (PO) ₃ ) 1, K of (2) ⁺ 、Ca ²⁺ In the case of (2) 1 kind selected from fluoride, carbonate and metaphosphate, cu ²⁺ 、Cu ⁺ In the case of CuO.

[ evaluation ]

The transmittance of light having a wavelength of 350 to 1200nm was measured by a spectrophotometer (V-570 manufactured by Japanese Spectrophotometer Co., ltd.). The measurement result was converted into a transmittance of 0.1mm in thickness by the above method. Tables 1 to 3 show the transmittance of light having a wavelength of 400nm, 420nm, and 1200nm in terms of thickness of 0.1 mm. Further, a wavelength (IR half peak) at which the transmittance in the near infrared ray region reaches 50% was calculated from the converted transmittance. In examples 13 to 18, since devitrification occurred, the transmittance was not measured (shown in table 2 as no data).

The solubility was evaluated by the following procedure. First, glass was melted at 800 to 900 ℃ for 2 hours, and the presence or absence of devitrification pits was visually confirmed on the glass in the molten state, and the presence or absence of devitrification pits was marked as "x", and the absence thereof was marked as "o".

Young's modulus was measured on glass having a thickness of 0.15 to 0.3mm by ultrasonic pulse method using an ultrasonic thickness meter (35 DL manufactured by Olympus Co., ltd.). The average value of the results after 2-point measurement is shown in tables 1 to 3.

TABLE 1

TABLE 2

TABLE 3

TABLE 3 Table 3

Further, the transmittance of example 8 (example) and example 19 (comparative example) converted to a plate thickness of 0.1mm is shown in FIG. 1.

In each of examples (examples 1 to 10 and examples 20 to 22) of the present application, glasses having good optical characteristics, no devitrification (good meltability), and a Young's modulus of 70GPa or more were obtained.

In contrast, in example 12, which is a comparative example, li ⁺ Content of (C/sigma R ')' ⁺ Less than 0.75, and thus becomes a glass having a low Young's modulus.

In examples 13 to 18, the content of (Ca ²⁺⁺ Ba ²⁺ )/ΣR ²⁺ Less than 0.75, thus producing devitrification.

The effect of Sr on the solubility was confirmed by the following method. Melting properties were confirmed by preparing glass obtained by subtracting a predetermined amount of Sr, ca, and Ba from glass of example 15 (example 11 (2% Sr reduction from example 15), example 16 (2% Ca reduction from example 15), and example 17 (2% Ba reduction from example 15). The results show that only example 11 has good melting properties, indicating that reducing Sr contributes to the improvement of melting properties.

The effect of Mg on the solubility was confirmed by the following method. A glass (example 10) was prepared from the glass of example 18 containing no Mg alone, and the melting property was confirmed. The results show that the glass of example 10 has good melting properties, indicating that reducing Mg contributes to the improvement of the melting properties.

Further, the influence of the content of Al on young's modulus was confirmed by the following method. The young's modulus between glasses of examples 20 to 22 was compared with that of examples 20 to 22 in which only the Al content was changed (the total of the cation% of the components other than Al was converted to 100%). As a result, as the Al content increases, the young's modulus of the glass increases, indicating that increasing the Al content within a certain range contributes to the increase in young's modulus.

Further, an embodiment of the present application is shown in table 4. Examples 23 to 29 are examples of the present application.

[ preparation of glass ]

The glass was weighed and mixed so that the composition of the glass after the melt molding became the composition shown in Table 4 (cation and anion%), placed in a platinum crucible having an internal volume of about 1L, melted at a temperature of 800 to 900℃for 1 to 4 hours, clarified, stirred, poured into a rectangular mold having a length of 100 mm. Times.80 mm. Times.20 mm and preheated to about 50 to 500℃and then cooled slowly to 360 to 440℃and cooled at about 1℃per minute to obtain a sample. Next, the front and back surfaces were optically polished to obtain glass having a thickness of 0.15 to 0.3 mm.

In addition, the materials for each glass are those described above. The evaluation method of each item is the method described above.

TABLE 4

TABLE 4 Table 4

In each of examples (examples 23 to 29) of the present application, glasses having good optical characteristics, no devitrification (good meltability), and a Young's modulus of 70GPa or more were obtained.

Further, the influence of the content of F on Young's modulus was confirmed by the following method. The young's modulus between glasses of examples 27 to 29, in which the F content was changed, was compared by using the same amount of glass raw material and changing only the melting time. As a result, as the content of F becomes smaller, the young's modulus of the glass increases, indicating that decreasing the amount of F within a certain range contributes to the increase in young's modulus.

Various embodiments are described above with reference to the drawings, but the application is not limited to these examples. It is apparent to those skilled in the art that various modifications and corrections can be made within the scope of the appended claims, and it should be understood that these modifications and corrections are also included in the technical scope of the present application. The various components in the above embodiments may be arbitrarily combined within a range not departing from the gist of the present application.

The present application is based on japanese patent application publication (2020-2177105) filed on even 25 th 12 th 2020, the contents of which are incorporated herein by reference.

Industrial applicability

According to the present application, the composition is not easily devitrified even when the Cu component content is large due to the reduction in the thickness, and the composition can be melted at a low temperature, so that the transmittance of light in the visible light range is improved, and therefore, the composition is very useful for the use of a near infrared cut filter in a miniaturized and thinned imaging device.

Claims

1. A fluorophosphate glass is characterized in that,

it contains P, F, O as essential component, cation%

Cu ²⁺ 5 to 14 percent,

(Ca ²⁺ content of +Ba ²⁺ Content of/(Σr) ²⁺ 0.75 to 1.0, wherein ΣR ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ Is used in combination with the total amount of (a),

Li ⁺ content of (3)/ΣR’ ⁺ 0.75 to 1.0 but not 1.0, wherein ΣR' ⁺ Refers to Li ⁺ 、Na ⁺ The Young's modulus of the total amount of the components (C) is 70GPa or more.

2. The fluorophosphate glass of claim 1, wherein Li ⁺ Content of (C/sigma R ')' ⁺ 0.8 to 0.9, wherein ΣR' ⁺ Refers to Li ⁺ 、Na ⁺ Is a combination of the above.

3. The fluorophosphate glass according to claim 1 or 2, characterized in that it comprises

Cation%:

P ⁵⁺ 30～60％、

Al ³⁺ 4～20％、

ΣR’ ⁺ 20～50％、

Li ⁺ 15～40％、

Na ⁺ 0.1～15％、

ΣR ²⁺ 1～20％、

Mg ²⁺ 0～5％、

Ca ²⁺ 0～10％、

Sr ²⁺ 0～5％、

Ba ²⁺ 0～10％、

Cu ²⁺ 5～14％；

anion%:

F ^- 20～60％、

O ^2- 40～80％，

wherein ΣR' ⁺ Refers to Li ⁺ 、Na ⁺ Sigma R ²⁺ Refers to Ba ²⁺ 、Sr ²⁺ 、Ca ²⁺ 、Mg ²⁺ Is a combination of the above.

4. Fluorophosphate glass according to claim 1 or 2, characterized in that it contains cation%:

P ⁵⁺ 30～60％、

Al ³⁺ 4～20％、

ΣR’ ⁺ 20～50％、

Li ⁺ 15～40％、

Na ⁺ 0.1～15％、

ΣR ²⁺ 1～20％、

Mg ²⁺ 0～5％、

Ca ²⁺ 0～10％、

Sr ²⁺ 0～5％、

Ba ²⁺ 0～10％、

Cu ²⁺ 5～14％；

anion%:

F ^- 5 to 20 percent but not 20 percent,

O ^2- 80-95% but not 80%,

5. The fluorophosphate glass according to any one of claim 1 to 4,

the thickness of the plate is 0.1mm,

the wavelength at which the transmittance reaches 50% is in the range of 600 to 670nm,

the transmittance of light with a wavelength of 400nm is 85% or more,

the transmittance of light with a wavelength of 1200nm is 40% or less.

6. A near infrared cut filter comprising the fluorophosphate glass according to any one of claims 1 to 5.