JP2015089855A - Near-infrared absorbing glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide near-infrared absorbing glass which is easily formed into a thin plate by an overflow downdraw method or the like and has high visible transmittance and high near-infrared ray absorbing ability.SOLUTION: There is provided near-infrared absorbing glass which comprises, by mass%, 40 to 70% of PO, 3 to 15% of AlO, 8 to 16% of KO, 5 to 25% of BaO, 2.5 to 10% of CuO, 0.1 to 1.0% of CeO+SbOand 0 to 5% of NaO and is formed into a thin plate by an overflow downdraw method or the like.

Description

  The present invention relates to near-infrared absorbing glass.

  Generally, near-infrared absorbing glass is used for a camera portion in a digital camera or a smartphone in order to correct the visibility of a solid-state imaging device such as a CCD or CMOS. In addition, in order to reduce the thickness and weight of the camera, it is desired to reduce the thickness of the near infrared absorbing glass. For example, Patent Document 1 discloses an infrared cut filter glass made of phosphate glass that does not contain fluoride.

JP2011-121792A

  The infrared cut filter glass described in Patent Document 1 has a melting temperature of 800 to 1100 ° C. and a liquidus temperature as high as 720 to 980 ° C. Therefore, when a thin plate is formed by an overflow downdraw method, a float method, or the like, there is a problem that the glass is easily devitrified.

  In view of the above, an object of the present invention is to provide a near-infrared absorbing glass that can be easily formed into a thin plate by an overflow downdraw method or the like, has high visible transmittance, and has high near-infrared absorbing ability.

Near-infrared-absorbing glass of the present invention, in _{mass%, P 2 O 5 40~70%} , Al 2 O 3 3~15%, K 2 O 8~16%, BaO 5~25%, CuO 2.5~ 10%, CeO ₂ + Sb ₂ O ₃ 0.1-1.0%, Na ₂ O 0-5%.

In the near-infrared absorbing glass of the present invention, K ₂ O / Al ₂ O ₃ is preferably 0.5 to 2.5 on a mass basis.

Near-infrared-absorbing glass of the present invention further contains, by _{mass%, MgO + CaO + SrO 0~5} %, 0~10% ZnO, Nb 2 O 5 0~3%, Y 2 O 3 0~3%, La 2 O 3 0 to _3%, preferably contains _Ta 2 O 5 _0~3%.

  The near-infrared absorbing glass of the present invention preferably has a thickness of 0.01 to 1.4 mm.

The near-infrared absorbing glass of the present invention preferably has a temperature at 10 ^4.0 dPa · s of 750 ° C. or lower.

Near-infrared-absorbing glass of the present ^invention, in the temperature at ¹⁰ 4.0 dPa · s, it is preferred that the devitrification does not occur.

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

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the near-infrared absorptive glass which is easy to shape | mold into a thin plate by the overflow downdraw method etc., and has high visible transmittance and a high near-infrared absorptivity.

  Below, the reason which limited the composition of the near-infrared absorption glass of this invention as mentioned above is demonstrated. In the description of each component below, “%” indicates “% by mass”.

P ₂ O ₅ is an essential component for forming a glass skeleton. The content of P ₂ O ₅ is 40 to 70%, preferably 50 to 65%, and more preferably 55 to 63%. When 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, the glass structure is chemically weakened, tends to be devitrified.

Al ₂ O ₃ is a component that stabilizes vitrification. The content of Al ₂ O ₃ is ₃ to 15%, preferably 6 to 12%, and more preferably 7.1 to 12%. If the content of Al ₂ O ₃ is too small, the above effect is difficult to obtain. On the other hand, if the content of Al ₂ O ₃ is too large, on the other hand, crystals due to Al ₂ O ₃ tend to precipitate during melting and molding, and vitrification becomes unstable.

K ₂ O is a component that lowers the melting temperature of the glass. The content of K ₂ O is 8 to 16%, preferably 10 to 15%. When the content of K ₂ O is too small, the melting temperature becomes high, so that Cu ions in the glass are easily reduced, and the ratio of Cu ⁺ is remarkably increased. As a result, it becomes difficult to obtain desired spectral characteristics. . On the other hand, when the content of K 2 _O is too large, K 2 _O resulting crystal tends to deposit in the molding, vitrification tends to be unstable.

  BaO is a component that stabilizes vitrification. The content of BaO is 5 to 25%, preferably 10 to 20%, and more preferably 12 to 18%. If the content of BaO is too small, the above effect is difficult to obtain. On the other hand, when there is too much content of BaO, the crystal | crystallization derived from BaO will precipitate easily during shaping | molding.

  CuO is a component that absorbs near infrared rays. The CuO content is 2.5 to 10%, preferably 3 to 9%, and more preferably 4 to 9%. If the content of CuO is too small, a thin plate cannot obtain a sufficient near infrared absorption ability. On the other hand, if the CuO content is too large, the transmittance in the ultraviolet to visible range tends to decrease.

CeO ₂ and Sb ₂ O ₃ are components that can lower the melting temperature of the glass and maintain a high proportion of Cu ²⁺ . The CeO ₂ and Sb ₂ O ₃ contents are 0.1 to 0.5% in total, and preferably 0.1 to 0.3%. If the content of these components is too small, the above effect is difficult to obtain. On the other hand, when there is too much content of these components, there exists a tendency for vitrification to become unstable.

Na ₂ O is a component that lowers the melting temperature of the glass. The content of Na ₂ O is 0 to 5%, preferably 0 to 3%. Na 2 _O content is too large when the vitrification tends to be unstable.

In order to stabilize the decrease in melting temperature and vitrification, it is preferable to keep K ₂ O / Al ₂ O ₃ within a certain range. Specifically, these component ratios are preferably 0.5 to 2.5 and more preferably 1 to 2 on a mass basis. When these component ratios are too small, the melting temperature tends to increase. On the other hand, when these component ratios are too large, devitrification increases and it becomes difficult to obtain a homogeneous glass.

  The near-infrared absorbing glass of the present invention can contain the following components in addition to the above components.

  MgO, CaO and SrO are components that stabilize vitrification. The total content of MgO, CaO and SrO is preferably 0 to 5%, more preferably 0 to 3%. When there is too much content of these components, the crystal | crystallization resulting from these components will precipitate easily during shaping | molding.

  ZnO can be contained for the purpose of adjusting the viscosity. The content of ZnO is preferably 0 to 10%, and more preferably 1 to 8%. When there is too much content of ZnO, vitrification will become unstable easily.

Nb ₂ O ₅ is a component that stabilizes vitrification. The content of Nb ₂ O ₅ is preferably 0 to 3%, and more preferably 0 to 2%. When the content of Nb ₂ O ₅ is too large, it decreases the meltability, the melting temperature becomes high, it is difficult to obtain the desired spectral characteristics.

Y ₂ O ₃ is a component that stabilizes vitrification. The content of Y ₂ O ₃ is preferably 0 to 3%, and more preferably 0 to 2%.

La ₂ O ₃ is a component that stabilizes vitrification. The content of La ₂ O ₃ is preferably 0 to 3%, and more preferably 0 to 2%.

Ta ₂ O ₅ is a component that enhances chemical durability. The content of Ta ₂ O ₅ is preferably 0 to 3%, and more preferably 0 to 2%.

In addition, it may be a Li 2 _O and B ₂ O ₃ or the like is contained in a range that does not impair the effects of the present invention. Specifically, the content of these components is preferably 0 to 3%, and more preferably 0 to 2%.

  The near-infrared absorbing glass of the present invention preferably has a flat plate shape, a plate thickness of preferably 0.01 to 1.4 mm, more preferably 0.05 to 0.5 mm, 0.1 More preferably, it is -0.3 mm. The smaller the plate thickness, the easier it is to manufacture a thin and light optical device such as a camera. However, when the plate thickness is extremely small, the glass is easily broken.

In the near-infrared absorbing glass of the present invention, the temperature at 10 ^4.0 dPa · s is preferably 750 ° C. or lower, more preferably 700 ° C. or lower, and further preferably 650 ° C. or lower. If the temperature at 10 ^4.0 dPa · s is too high, the melting temperature tends to increase, so that Cu ions in the glass are likely to be reduced, and the proportion of Cu ⁺ is significantly increased. As a result, desired spectral characteristics are obtained. It becomes difficult to obtain. The “temperature at 10 ^4.0 dPa · s” represents the temperature of the glass when the viscosity of the glass is 10 ^4.0 dPa · s.

Near-infrared-absorbing glass of the present ^invention, in the temperature at ¹⁰ 4.0 dPa · s, it is preferred that the devitrification does not occur. By setting it as the said structure, it becomes difficult to devitrify glass at the time of shaping | molding, and it becomes easy to shape | mold a glass plate by the overflow downdraw method, the float glass method, etc.

  The near-infrared absorbing glass of the present invention is preferably formed by a down draw method, particularly an overflow down draw method. In this way, it is possible to manufacture a glass plate that is unpolished and has good surface quality at a low cost and in large quantities. Further, it becomes easy to increase the size and thickness of the glass plate. In addition to the overflow downdraw method, a slot downdraw method can be employed. If it does in this way, it will become easy to produce a glass plate with small board thickness. Here, the “slot down draw method” is a method of forming a glass plate by drawing downward from a substantially rectangular gap while drawing molten glass.

  In addition to the above molding method, for example, a redraw method, a float method, a roll-out method, or the like can be employed. In particular, the float method can efficiently produce a large glass plate.

  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.

(1) Production of Samples Tables 1 and 2 show examples (Nos. 1 to 12) and comparative examples (Nos. 13 to 15) of the present invention.

  Each sample was produced as follows.

  First, the glass raw material prepared so that it might become the composition as described in each table | surface was thrown into the platinum crucible, and it melted so that it might become homogeneous at 900-1000 degreeC. Next, the molten glass was poured out on the carbon plate, cooled and solidified, and then annealed to prepare a sample.

(2) Evaluation The resulting samples of each sample, the light transmittance, temperature at 10 4.0 ^{dPa · s,} was measured or evaluated by the following methods devitrification resistance. The results are shown in Tables 1 and 2.

The light transmittance was measured in the range of 300 to 1500 nm using a U-4100 manufactured by Hitachi, Ltd. for a 12 × 20 × 0.3 mm sample whose both surfaces were mirror-polished. λ ₅₀ is a wavelength at which the light transmittance is 50% in the wavelength range of 500 to 700 nm of the obtained light transmittance curve.

The measurement of temperature at 10 ^4.0 dPa · s was performed as follows. First, the sample was crushed to an appropriate size and put into a platinum crucible so that bubbles were not caught as much as possible. Subsequently, the platinum crucible was heated to bring the sample into a molten state, and the viscosity of the glass at a plurality of temperatures was determined by a platinum ball pulling method. Thereafter, a viscosity curve was created from the obtained plurality of measured values, and the temperature at which the viscosity was 10 ^4.0 dPa · s was calculated by interpolation.

The devitrification resistance was measured by putting an appropriate amount of the crushed sample into a platinum crucible equivalent to 100 cc, heating at 900 to 1000 ° C. for 30 minutes, and temperature at 10 ^4.0 dPa · s over 5 to 10 hours. The glass interior and the platinum interface were observed using an optical microscope, and no devitrification was observed in the glass interior or platinum interface. The case where devitrification was confirmed at the platinum interface was evaluated as “x”.

(3) Discussion of results No. as an example. Nos. 1 to 12 had a temperature at 10 ^4.0 dPa · s as low as 681 ° C. or less and good devitrification resistance, and therefore could be molded by the overflow down draw method. In addition, the transmittance at a wavelength of 500 nm was 85% or more, the transmittance at a wavelength of 700 nm was 10% or less, and λ ₅₀ was 601 nm to 640 nm. On the other hand, No. which is a comparative example. Nos. 13 and 14 generate a large amount of devitrification at the time of melting of the glass and cannot be vitrified. In Comparative Example 15, the devitrification resistance was poor, and therefore, molding by the overflow downdraw method is difficult.

  The near-infrared absorbing glass of the present invention is a lens of a digital camera, a CCD cover glass, a heat ray absorbing glass used for a CCD or CMOS, and further an IR / UV absorbing glass, a visibility correction filter, a color adjustment filter, etc. It can be used for an optical filter or the like.

Claims (7)

By _{mass%, P 2 O 5 40~70%} , Al 2 O 3 3~15%, K 2 O 8~16%, BaO 5~25%, CuO 2.5~10%, CeO 2 + Sb 2 O 3 A near infrared ray absorbing glass containing 0.1 to 1.0% and Na ₂ O 0 to 5%. The near-infrared absorbing glass according to claim 1, wherein K ₂ O / Al ₂ O ₃ is 0.5 to 2.5 on a mass basis. Moreover, in _{mass%, MgO + CaO + SrO 0~5} %, 0~10% ZnO, Nb 2 O 5 0~3%, Y 2 O 3 0~3%, La 2 O 3 0~3%, Ta 2 O 5 0 The near-infrared absorbing glass according to claim 1, comprising ˜3%.   Plate | board thickness is 0.01-1.4 mm, The near-infrared absorption glass as described in any one of Claims 1-3 characterized by the above-mentioned. The near-infrared absorbing glass according to claim 1, wherein the temperature at 10 ^4.0 dPa · s is 750 ° C. or lower. The near-infrared absorbing glass according to claim 1, wherein devitrification does not occur at a temperature of 10 ^4.0 dPa · s. The near-infrared absorbing glass according to claim 1, which is formed by an overflow downdraw method.