JP2019038719A - Near-infrared radiation absorption glass - Google Patents

Abstract

To provide a near-infrared radiation absorption glass, the use of which enables a reduction in the thickness of an optical device and which demonstrates excellent characteristics such as weather resistance, devitrification resistance, and optical properties even without the inclusion of fluorine.SOLUTION: The near-infrared radiation absorption glass has, in percentage by mass, 20 to 80% of PO, 1 to 50% of RO (where R represents at least one selected from among Mg, Ca, Sr and Ba), 0.1 to 30% of MgO, 0 to 15% of NaO, 0 to less than 14% of KO, and 0.1 to 30% of CuO, and a thickness being 0.25 mm or less.SELECTED DRAWING: None

Description

  The present invention relates to a near infrared ray absorbing glass capable of selectively absorbing near infrared rays.

  In general, near-infrared absorbing glass is used in a camera portion in an optical device such as a digital camera or a smartphone for the purpose of correcting the visibility of a solid-state imaging device such as a CCD or CMOS. For example, Patent Document 1 discloses a phosphoric acid-based near-infrared absorbing glass containing fluorine. Since fluorine has a high effect of improving weather resistance, the near-infrared absorbing glass described in Patent Document 1 is excellent in weather resistance.

JP 2004-83290 A

  Since the fluorine component is an environmentally hazardous substance, its use is being restricted in recent years. However, when it does not contain a fluorine component, it is difficult to improve the weather resistance, and when it is attempted to improve the weather resistance, problems such as a decrease in devitrification resistance and optical characteristics tend to occur. In recent years, thinning of optical devices has been strongly desired, and it is necessary to make the near-infrared absorbing glass thin. However, in order to produce a thin near-infrared absorbing glass, higher devitrification resistance is required.

  In view of the above, the present invention provides a near-infrared absorptive glass that is excellent in weather resistance, devitrification resistance, and optical characteristics even when the optical device can be thinned and does not contain fluorine. For the purpose.

The near-infrared absorbing glass of the present invention is in mass%, P ₂ O ₅ 20-80%, RO (however, R is at least one selected from Mg, Ca, Sr and Ba) 1-50%, MgO 0. It contains 1 to 30%, Na ₂ O 0 to 15%, K ₂ O 0 to less than 14%, and CuO 0.1 to 30%, and has a thickness of 0.25 mm or less.

The near-infrared absorbing glass of the present invention regulates RO for improving devitrification resistance to 1% or more, Na ₂ O for reducing devitrification resistance to 15% or less, and K ₂ O to less than 14%, High devitrification resistance is achieved. Therefore, the present invention can also be applied to molding methods that are likely to cause devitrification, such as a downdraw method and a redraw method, which can efficiently manufacture a thin infrared absorbing glass.

The near-infrared absorbing glass of the present invention further preferably contains Al ₂ O _{3 0 to} 19% and ZnO 0 to 13% by mass.

  The near-infrared absorbing glass of the present invention preferably contains no fluorine component. Here, “does not contain a fluorine component” means that it is not intentionally contained, and does not exclude inevitable contamination. Specifically, it means that the content of the fluorine component is 1000 ppm or less.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where an optical device can be made thin and it is a case where it does not contain a fluorine, it is providing the near-infrared absorption glass excellent in each characteristic of a weather resistance, devitrification resistance, and an optical characteristic. It becomes possible.

The near-infrared absorbing glass of the present invention is 20 to 80% P ₂ O ₅ , RO (where R is at least one selected from Mg, Ca, Sr and Ba) 1 to 50%, MgO 0.1 to 30% , _Na 2 O _0~15%, K less than 2 O 0 to 14%, and containing 0.1 to 30% CuO. The reason for limiting the glass composition as described above will be described below. In the following description regarding the content of each component, “%” means “mass%” unless otherwise specified.

P ₂ O ₅ is an essential component for forming a glass skeleton. The content of P ₂ O ₅ is 20 to 80%, 31 to 73%, and particularly preferably 45 to 67%. If the content of P ₂ O ₅ is too small, there is a tendency for vitrification tends to be unstable. On the other hand, when the content of P ₂ O ₅ is too large, lowered resistance to devitrification liquidus viscosity is low, the weather resistance tends to lower.

  RO (where R is at least one selected from Mg, Ca, Sr, and Ba) is a component that improves devitrification resistance and weather resistance. The total RO content is 1 to 50%, preferably 3 to 34%, particularly preferably 6 to 20%. If the RO content is too small, the above effects are difficult to obtain. On the other hand, when there is too much content of RO, devitrification resistance will fall and the crystal | crystallization resulting from RO component will precipitate easily.

  In addition, the preferable range of content of each component of RO is as follows.

  MgO is a component that improves devitrification resistance and weather resistance. The content of MgO is preferably 0.1 to 30%, particularly preferably 0.4 to 13%. If the content of MgO is too small, the above effect is difficult to obtain. On the other hand, when there is too much content of MgO, stability of vitrification will fall easily.

  CaO, like MgO, is a component that improves devitrification resistance and weather resistance. The CaO content is preferably 0 to 15%, particularly preferably 0.4 to 7%. When there is too much content of CaO, stability of vitrification will fall easily.

  SrO, like MgO, is a component that improves devitrification resistance and weather resistance. The SrO content is preferably 0 to 12%, particularly preferably 0.3 to 6%. When there is too much content of SrO, stability of vitrification will fall easily.

  BaO, like MgO, is a component that improves devitrification resistance and weather resistance. The content of BaO is preferably 0 to 30%, 1 to 25%, particularly 3 to 20%. When there is too much content of BaO, the crystal | crystallization resulting from BaO will precipitate easily during shaping | molding.

As described above, RO has an effect of improving devitrification resistance, and when the amount of P ₂ O ₅ is small, it is easy to enjoy the effect.

Na ₂ O is a component that lowers the melting temperature. The content of Na ₂ O is 0 to 15%, and particularly preferably 0.1 to 10%. When the content of Na 2 _O is too large, the devitrification resistance tends to decrease.

K ₂ O is a component that lowers the melting temperature in the same manner as Na ₂ O. The content of K ₂ O is 0 to less than 14%, particularly preferably 0.1 to 12%. When the content of K 2 _O is too large, K 2 _O resulting crystal tends to deposit in the molding, the devitrification resistance tends to decrease.

  CuO is an essential component for absorbing near infrared rays. The CuO content is preferably 0.1 to 30%, 0.3 to 20%, 2 to 15%, particularly 3 to 13%. When there is too little content of CuO, it will become difficult to obtain a desired near-infrared absorption characteristic. On the other hand, when there is too much content of CuO, the light transmittance of an ultraviolet-visible range will fall easily. Moreover, there exists a tendency for devitrification resistance to fall.

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

Al ₂ O ₃ is a component that improves weather resistance, increases liquid phase viscosity, and improves devitrification resistance. The content of Al ₂ O ₃ is preferably 0 to 19%, 2 to 19%, 3 to 14%, particularly 3 to 9%. When the content of Al ₂ O ₃ is too large, there is a tendency that the melting temperature fusible reduced increases. Note that when the melting temperature rises, Cu ions are reduced and easily shift from Cu ²⁺ to Cu ⁺ , making it difficult to obtain desired optical characteristics. Specifically, the light transmittance in the near ultraviolet to visible range is lowered, and the near infrared absorption characteristics are liable to be lowered.

  ZnO is a component that improves devitrification resistance and weather resistance. The content of ZnO is preferably 0 to 13%, 0.1 to 12%, particularly preferably 1 to 10%. When there is too much content of ZnO, a meltability will fall and a melting temperature will become high, and it will become difficult to obtain a desired optical characteristic as a result. In addition, crystals derived from ZnO tend to precipitate during molding, and the devitrification resistance tends to decrease.

Li ₂ O is a component that lowers the melting temperature. The content of Li ₂ O is 0 to 15%, and particularly preferably 0.1 to 10%. The content of Li 2 _O is too large, the devitrification resistance tends to decrease.

Further, in addition to the above components, B ₂ O ₃ , Nb ₂ O ₅ , Y ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ₅ , CeO ₂ , Sb ₂ O _{3 and the} like do not impair the effects of the present invention. You may make it contain. Specifically, the content of these components is preferably 0 to 3%, particularly 0 to 2%. In addition, since a fluorine component is an environmental impact substance, it is preferable not to contain.

  The near infrared ray absorbing glass of the present invention is usually used in a plate shape. The thickness is 0.25 mm or less, preferably 0.2 mm or less, 0.15 mm or less, particularly preferably 0.1 mm or less. If the thickness is too large, it is difficult to reduce the thickness of the optical device. In addition, although the minimum of thickness is not specifically limited, From a viewpoint of mechanical strength, it is preferable that it is 0.01 mm or more.

  By having the above composition, the near-infrared absorbing glass of the present invention can achieve both high light transmittance in the visible range and excellent light absorption characteristics in the near-infrared range. Specifically, the light transmittance at a wavelength of 500 nm is preferably 75% or more, particularly 77% or more. On the other hand, the light transmittance at a wavelength of 700 nm is preferably 30% or less, particularly preferably 28% or less, and the light transmittance at a wavelength of 1200 nm is preferably 40% or less, particularly preferably 38% or less.

The near-infrared absorbing glass of the present invention preferably has a liquidus viscosity of 10 ^1.6 dPa · s or more, particularly 10 ^1.9 dPa · s or more. If the liquid phase viscosity is too low, it tends to devitrify during molding.

The near-infrared absorbing glass of the present invention can be produced by melting and molding a raw material powder batch prepared to have a desired composition. The melting temperature is preferably 900 to 1200 ° C. If 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 that it becomes 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 purposes. In order to efficiently produce a near-infrared absorbing glass having a small thickness, it is preferable to apply a molding method such as a downdraw method or a redraw method. Since these forming methods are easily 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 (Sample Nos. 1 to 8) and Comparative Examples (Sample Nos. 9 and 10) of the present invention.

(1) Preparation of each sample First, the glass raw material prepared so that it might become the composition of Table 1 was thrown into the platinum crucible, and it fuse | melted at the temperature of 1000-1200 degreeC. 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 with the following method. The results are shown in Table 1.

  For the light transmission characteristics, the transmittances at wavelengths of 500 nm, 700 nm, and 1200 nm were measured using a spectroscopic analyzer (UV3100, manufactured by Shimadzu Corporation) for the samples having the thicknesses shown in Table 1 whose surfaces were mirror-polished. It should be noted that if the transmittances at wavelengths of 500 nm, 700 nm, and 1200 nm are 77% or more, 28% or less, and 38% or less, respectively, it can be determined that the light transmission characteristics are good.

  The weather resistance was determined by the presence or absence of a change in appearance of a sample whose both surfaces were mirror-polished after being held for 24 hours under conditions of a temperature of 120 ° C. and a relative humidity of 100%. Specifically, “◯” indicates that no change in appearance was observed after the test, and “×” indicates change in appearance such as white discoloration.

  The liquid phase viscosity was determined as follows. A sample crushed so as to have a particle size of 300 to 600 μm was placed in a platinum container and held in a temperature gradient furnace for 24 hours. The maximum temperature at which the interface crystals were precipitated on the bottom surface of the platinum container was defined as the liquidus temperature. The viscosity of the sample was measured, and the viscosity at the liquidus temperature was defined as the liquidus viscosity.

As is apparent from Table 1, No. 1 as an example of the present invention. Samples 1 to 8 had a high light transmittance in the visible range and a large absorption in the near infrared range. Further, no change was observed before and after the test in the weather resistance evaluation, and the liquid phase viscosity was 10 ^1.6 dPa · s or more, and the devitrification resistance was excellent. Since the thickness is 0.23 mm or less, the optical device can be easily thinned.

On the other hand, No. which is a comparative example. The sample of 9 was inferior in weather resistance, and was inferior in devitrification resistance because the liquid phase viscosity was 10 ^1.2 dPa · s. No. The sample No. 10 was inferior in devitrification resistance because the liquid phase viscosity was 10 ^1.3 dPa · s.

Claims (3)

By _{mass%, P 2 O 5 20~80%} , RO ( provided that at least one R is selected from Mg, Ca, Sr and Ba) 1~50%, 0.1~30% MgO , Na 2 O 0 to _15%, K less than 2 O 0 to 14%, and containing 0.1 to 30% CuO, near-infrared absorbing glass wherein the thickness is 0.25mm or less. Moreover, in _{mass%, Al 2 O 3 0~19%} , near-infrared-absorbing glass as claimed in claim 1, characterized in that it contains 0 to 13% ZnO.   The near-infrared absorbing glass according to claim 1 or 2, which does not contain a fluorine component.