WO2019044324A1 - Near infrared ray absorbing glass - Google Patents

Abstract

Provided is a near infrared ray absorbing glass which enables thinner optical devices and has excellent weather resistance, devitrification resistance, and optical properties. The near infrared ray absorbing glass comprises, in cation%, 10 to 70% P5 +, 0 to less than 7% Na+, 3 to less than 31% R2+ (R is at least one selected from Mg, Ca, Sr, and Ba), 0.1 to 20% Mg2+, 2 to 20% Sr2+, and 0.1 to less than 9% Cu2+, and in anion%, 14.5 to 90% F- and 10 to 85.5% O2-, and is characterized by having a thickness of 0.25 mm or less.

Description

Near infrared absorbing glass

The present invention relates to a near-infrared absorbing glass capable of selectively absorbing near-infrared light.

In general, near-infrared absorbing glass is used for camera parts in optical devices such as digital cameras and smartphones for the purpose of correcting the visibility of solid-state imaging devices such as CCDs and CMOS. For example, Patent Document 1 discloses a phosphate-based near-infrared absorbing glass containing fluorine.

JP 2004-137100 A

In recent years, it has been strongly desired to reduce the thickness of optical devices, and it is necessary to reduce the thickness of near-infrared absorbing glass. However, high devitrification resistance is required to produce thin near-infrared absorbing glass. However, when trying to improve the devitrification resistance, problems such as deterioration of weatherability, optical characteristics and the like tend to occur.

In view of the above, it is an object of the present invention to provide a near-infrared absorbing glass which can reduce the thickness of an optical device and is excellent in the devitrification resistance, weather resistance and optical characteristics.

The near-infrared absorbing glass of the present invention is, in cation%, P 5 ⁺ 10 to 70%, Na ⁺ 0 to less than 7%, R 2 ⁺ 3 to less than 31% (R is at least selected from Mg, Ca, Sr and Ba ^{one), Mg 2+ 0.1 ~ 20%} , Sr 2+ 2 ~ 20%, Cu 2+ 0.1 to less than 9% and, by ^{anionic%, F - 14.5 ~ 90%} , O 2- 10 ~ It is characterized by containing 85.5% and having a thickness of 0.25 mm or less.

The near-infrared absorbing glass of the present invention achieves high devitrification resistance by regulating R ²⁺ to improve devitrification resistance to 3% or more and Na ⁺ to reduce devitrification resistance to less than 7%. ing. Therefore, it can apply also to the forming method which tends to be accompanied by devitrification, such as the down draw method which can manufacture efficiently infrared absorption glass with small thickness, and a redraw method.

The near-infrared absorbing glass of the present invention preferably further contains 0 to 10% of Zn ²⁺ at cation%.

The near-infrared absorbing glass of the present invention preferably contains substantially no Pb component and As component. In addition, "does not substantially contain" means not intentionally containing as a raw material, and means that content of each component is less than 0.1% objectively.

According to the present invention, it is possible to provide a near-infrared absorbing glass which can reduce the thickness of an optical device and is excellent in the devitrification resistance, the weather resistance and the optical characteristics.

The near-infrared absorbing glass of the present invention is, in cation%, P 5 ⁺ 10 to 70%, Na ⁺ 0 to less than 7%, R 2 ⁺ 3 to less than 31% (R is at least selected from Mg, Ca, Sr and Ba) ^{one), Mg 2+ 0.1 ~ 20%} , Sr 2+ 2 ~ 20%, containing Cu 2+ 0.1 to less than 9%. Below, the reason which limited the glass composition as mentioned above is demonstrated.

P ⁵⁺ is an essential component for forming a glass skeleton. The content of P ⁵⁺ is 10 to 70%, preferably 15 to 63%, 18 to 51%, 25 to 50%, particularly 25 to 40%. If the content of P ⁵⁺ is too low, vitrification tends to be unstable. On the other hand, when the content of P ⁵⁺ is too large, the weather resistance tends to be lowered.

Na ⁺ is a component that lowers the melting temperature. The content of Na ⁺ is 0 to less than 7%, preferably 0.1 to 6%, 0 to 2%, and particularly preferably not contained. When the content of Na ⁺ is too large, the devitrification resistance and the weather resistance tend to be lowered.

R ²⁺ (R is at least one selected from Mg, Ca, Sr and Ba) is a component that improves the devitrification resistance and the weather resistance. The total content of R ²⁺ is preferably 3 to less than 31%, more preferably 8 to 28%, and particularly preferably 12 to 26%. When the content of R ²⁺ is too small, the above effect is hardly obtained. On the other hand, when the content of R ²⁺ is too large, the stability of vitrification tends to be reduced.

In addition, content of each component of R <^2+> is as follows.

Mg ²⁺ is a component that improves the devitrification resistance and the weather resistance. The content of Mg ²⁺ is preferably 0.1 to 20%, particularly preferably 3 to 11%. When the content of Mg ²⁺ is too low, the above effect is hardly obtained. On the other hand, when the content of Mg ²⁺ is too large, the stability of vitrification tends to be reduced.

Ca ²⁺ is a component that improves the devitrification resistance and the weather resistance as well as Mg ²⁺ . The content of Ca ²⁺ is preferably 0 to 12%, particularly 0.1 to 10%. When the content of Ca ²⁺ is too large, the stability of vitrification tends to be reduced.

Sr ^{2+ is} also a component that improves the devitrification resistance and the weather resistance, similarly to Mg ²⁺ . The content of Sr ²⁺ is preferably 2 to 20%, particularly preferably 2 to 10%. When the content of Sr ²⁺ is too small, the above effect is hardly obtained. On the other hand, when the content of Sr ²⁺ is too large, the stability of vitrification tends to be reduced.

Ba ^{2+ is} also a component that improves the devitrification resistance and the weather resistance, similarly to Mg ²⁺ . The content of Ba ²⁺ is preferably 0 to 10%, particularly 0.1 to 9%. When the content of Ba ²⁺ is too large, the stability of vitrification tends to be reduced.

Cu ²⁺ is an essential component for absorbing near infrared light. The content of Cu ²⁺ is preferably 0.1 to less than 9%, more preferably 2 to less than 9%, and particularly preferably 5 to less than 9%. When the content of Cu ²⁺ is too low, the above effect is hardly obtained. On the other hand, when the content of Cu ²⁺ is too large, the light transmittance in the ultraviolet to visible region is likely to decrease. In addition, the devitrification resistance tends to decrease.

In addition to the above components, various components shown below can be contained.

Al ³⁺ is a component that improves chemical durability. The content of Al ³⁺ is preferably 0 to 20%, 2 to 19%, 6 to 18%, 7 to 17%, particularly 8 to 16%. If the content of Al ³⁺ is too large, the meltability tends to decrease and the melt temperature tends to rise. Note that, when the melting temperature rises, Cu ions are reduced and it is easy to shift from Cu ²⁺ to Cu ⁺ , so it is difficult to obtain desired optical characteristics. Specifically, the light transmittance in the near ultraviolet to visible region is likely to be reduced, and the near infrared absorption characteristics are likely to be degraded.

Zn ²⁺ is a component that improves devitrification resistance and weatherability. The content of Zn ²⁺ is preferably 0 to 10%, particularly 0.1 to 5%. When the content of Zn ²⁺ is too large, the stability of vitrification tends to be reduced.

Li ⁺ is a component that lowers the melting temperature. The content of Li ⁺ is preferably 0 to 30%, particularly 0.1 to 25%. When the content of Li ⁺ is too large, the devitrification resistance tends to decrease.

K ⁺ is a component that lowers the melting temperature. The content of K ⁺ is preferably 0 to 30%, particularly 0.1 to 20%. When the content of K ⁺ is too large, the devitrification resistance tends to decrease.

In addition, the optical glass of the present invention, as the cationic ^{component, Bi 3+, La 3+, Y} 3+, Gd 3+, Te 4+, Si 4+, Ta 5+, Nb 5+, Ti 4+, and ^{Zr 4+} or ^{Sb 3+,} etc., You may make it contain in the range which does not impair the effect of this invention. Specifically, the content of each of these components is preferably 0 to 3%, and more preferably 0 to 1%.

The Pb component (Pb ^{2+ and the} like) and the As component (As ^{3 + and the} like) are environmentally hazardous substances, and therefore are preferably not substantially contained in the invention.

The composition of the anionic ^component, F - 14.5 ~ ^90%, and ^contains a O 2- 10 ~ 85.5%, in particular ^F - 20 ~ 70%, ^and, containing O 2- 30 ~ 80% It is preferable to do. If the content of F ⁻ is too small (the content of O ^{2 −} is too large), the devitrification resistance and the weather resistance tend to be lowered. On the other hand, F ^- the content is too high (O content of ² is too small), the stability of vitrification tends to decrease.

The near-infrared absorbing glass of the present invention is usually used in the form of a plate. The thickness is 0.25 mm or less, preferably 0.2 mm or less, 0.15 mm or less, and particularly 0.1 mm or less. If the thickness is too large, thinning of the optical device becomes difficult. The lower limit of the thickness is not particularly limited, but is preferably 0.01 mm or more from the viewpoint of mechanical strength.

By having the above-described composition, the near-infrared absorbing glass of the present invention can achieve both high light transmittance in the visible region and excellent light-absorbing characteristics in the near-infrared region. Specifically, the light transmittance at a wavelength of 500 nm is preferably 75% or more, and particularly preferably 77% or more. On the other hand, the light transmittance at a wavelength of 700 nm is preferably 28% or less, particularly preferably 26% or less, and the light transmittance at a wavelength of 1200 nm is preferably 39% or less, particularly preferably 37% or less.

The liquidus viscosity of the near-infrared absorbing glass of the present invention is preferably 10 ^0.8 dPa · s or more, and more preferably 10 ^1.0 dPa · s or more. If the liquidus viscosity is too low, devitrification tends to occur during molding.

The near-infrared absorbing glass of the present invention can be produced by melting and shaping a raw material powder batch prepared to have a desired composition. The melting temperature is preferably 700 to 900 ° C. When the melting temperature is too low, it is difficult to obtain a homogeneous glass. On the other hand, if the melting temperature is too high, Cu ions are reduced and it is easy to shift from Cu ²⁺ to Cu ⁺ , so it is difficult to obtain desired optical characteristics.

Thereafter, the molten glass can be formed into a predetermined shape, subjected to necessary post-processing, and used for various applications. In addition, in order to manufacture the near-infrared absorption glass with small thickness efficiently, it is preferable to apply molding methods, such as the down draw method and the redraw method. Since these forming methods are likely to be accompanied by devitrification, it is easy to enjoy the effect of the near-infrared absorbing glass of the present invention which is excellent in devitrification resistance.

Hereinafter, although the near-infrared absorption glass of this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

Table 1 shows Examples of the present invention (Sample Nos. 1 to 6) and Comparative Examples (Sample Nos. 7 to 9).

(1) Preparation of Each Sample First, a glass raw material prepared to have the composition shown in Table 1 was put into a platinum crucible and melted at a temperature of 700 to 850.degree. Next, the molten glass was poured onto a carbon plate and cooled and solidified. Thereafter, annealing was performed to obtain a sample.

(2) Evaluation of each sample About each obtained sample, the light transmission characteristic, the weather resistance, and the liquid phase viscosity were measured or evaluated by the following methods. The results are shown in Table 1.

The light transmission characteristics of each of the samples of the thickness described in Table 1 mirror-polished on both sides were measured with respective transmittances at wavelengths of 500 nm, 700 nm, and 1200 nm using a spectral analyzer (UV3100 manufactured by Shimadzu Corporation). If the transmittances at wavelengths of 500 nm, 700 nm, and 1200 nm are 77% or more, 26% or less, and 37% or less, respectively, it can be determined that the light transmission characteristics are good.

The weather resistance of the sample mirror-polished on both sides was determined under the conditions of a temperature of 120 ° C. and a relative humidity of 100% for 24 hours, and then judged by the presence or absence of a change in appearance. Specifically, those in which no change in appearance was observed after the test were evaluated as “○”, and those in which changes in appearance such as white discoloration were observed were evaluated as “x”.

The liquid phase viscosity was determined as follows. The sample crushed to a particle size of 300 to 600 μm was placed in a platinum container and kept in a temperature gradient furnace for 24 hours. The maximum temperature at which interfacial crystals were deposited on the bottom of the platinum container was taken as the liquidus temperature. The viscosity of the sample was then measured, and the viscosity at the liquidus temperature was taken as the liquidus viscosity.

As apparent from Table 1, No. 1 which is an embodiment of the present invention. Samples 1 to 6 had high light transmittance in the visible region and large absorption in the near infrared region. Further, no change was observed before and after the test in the weather resistance evaluation, and the liquid phase viscosity was 10 ^0.8 dPa · s or more, and the devitrification resistance was also excellent. In addition, since thickness is 0.24 mm or less, it is easy to make an optical device thin.

On the other hand, No. 1 which is a comparative example. The sample No. 7 was inferior in devitrification resistance because the liquidus viscosity was 10 ^0.4 dPa · s. No. The sample No. 8 was inferior in weather resistance and inferior in devitrification resistance because the liquidus viscosity was 10 ^0.6 dPa · s. No. The nine samples were not vitrified.

Claims (3)

In cation%, P 5 ⁺ 10 to 70%, Na ⁺ 0 to less than 7%, R 2 ⁺ 3 to less than 31% (R is at least one selected from Mg, Ca, Sr and Ba), Mg ²⁺ 0.1 ^{~ 20%, Sr 2+ 2 ~} 20%, Cu 2+ 0.1 to less than 9% and, by ^{anionic%, F - 14.5 ~ 90%} , contains O 2- 10 ~ 85.5%, the thickness Near-infrared absorbing glass characterized by having a diameter of 0.25 mm or less. The near-infrared absorbing glass according to claim 1, further comprising 0 to 10% of Zn ²⁺ at a cation%. The near-infrared absorbing glass according to claim 1 or 2, which is substantially free of Pb component and As component.