JP2009120485A - Optical glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high refractive index and high dispersion optical glass containing no Pb compound whose harmful effect to environment and human body is feared, economically efficient, and suitable for mass production. <P>SOLUTION: This optical glass contains not less than 1 wt.% but not more than 9.9 wt.% SiO<SB>2</SB>, not less than 10.5 wt.% but less than 35 wt.% B<SB>2</SB>O<SB>3</SB>, not less than 13 wt.% but less than 30 wt.% BaO, not less than 10 wt.% but less than 40 wt.% La<SB>2</SB>O<SB>3</SB>, not less than 8.9 wt.% but less than 15 wt.% TiO<SB>2</SB>, 0-less than 20 wt.% Nb<SB>2</SB>O<SB>5</SB>, 0-not more than 1.5 wt.% Ta<SB>2</SB>O<SB>5</SB>, 0-less than 10 wt.% WO<SB>3</SB>, 0-less than 10 wt.% ZrO<SB>2</SB>, 0-less than 10 wt.% MgO, 0-not more than 6.8 wt.% CaO, 0-less than 10 wt.% SrO, 0-less than 20 wt.% ZnO, 0-less than 2 wt.% Li<SB>2</SB>O+Na<SB>2</SB>O+K<SB>2</SB>O, 0-less than 15 wt.% Y<SB>2</SB>O<SB>3</SB>, 0-less than 15 wt.% Gd<SB>2</SB>O<SB>3</SB>, 0-less than 10 wt.% Yb<SB>2</SB>O<SB>3</SB>, 0-less than 5 wt.% Al<SB>2</SB>O<SB>3</SB>, and 0-less than 1 wt.% Sb<SB>2</SB>O<SB>3</SB>in the optical glass and contains no PbO. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical glass having a high refractive index and high dispersion.

  A composition containing a lead compound is generally well known as an optical glass having a high refractive index and high dispersion, and has been produced in large quantities. However, there is an environmental problem due to the strong toxicity of lead, and in recent years, a composition containing no lead has been strongly desired. There have been proposals for high-refractive index, high-dispersion optical glasses that do not contain lead, but they are not satisfactory in terms of economy and mass productivity and have practical upper limits.

As a composition for obtaining an optical glass having a high refractive index and high dispersion without containing a lead compound, for example, B ₂ O ₃ —SiO ₂ —La ₂ O ₃ —ZrO ₂ — (Nb ₂ O ₅ / Ta ₂ O ₅ ) -based optics The glass proposal [see, for example, Patent Document 1] is a composition that does not contain BaO and contains a large amount of La ₂ O _3, and therefore has poor meltability and devitrification stability and is an expensive component, Nb ₂ Since O ₅ and Ta ₂ O ₅ are contained in a large amount of 14% by weight or more in total, economy becomes a problem. In the proposal of SiO ₂ —B ₂ O ₃ —CaO—La ₂ O ₃ —ZrO ₂ —TiO ₂ —Nb ₂ O ₅ —alkali metal oxide optical glass (see, for example, Patent Document 2), an alkali metal oxide is used. Since it is 2% by weight or more, the chemical durability is lowered, the amount of volatilization at the time of melting is large, and the viscosity at the time of melting is excessively lowered, so that the devitrification stability and the glass formability may be lowered. _{SiO 2 -B 2 O 3 -La 2} O 3 -Nb 2 O 5 -ZrO 2 -TiO 2 - In proposal of an alkaline earth metal oxide optical glass [see, for example, Patent Document 3], SiO ₂ is _{B 2} It is more than O ₃ , has poor meltability, and tends to produce an unmelted product. Moreover, in order to ensure devitrification stability, introduction of Nb ₂ O ₅ which is an expensive component is essential. In the proposal of the B ₂ O ₃ —La ₂ O ₃ —ZnO—Li ₂ O—Sb ₂ O ₃ optical glass [see, for example, Patent Document 4], Sb ₂ O ₃ is contained in a large amount of 2 to 20% by weight. It is highly reducible, and the glass tends to be colored amber and lacks practicality. In the proposal of SiO ₂ —B ₂ O ₃ —La ₂ O ₃ —TiO ₂ —CaO optical glass (see, for example, Patent Document 5), TiO ₂ is contained in a large amount of 19 to 31% by weight in order to increase the refractive index. Therefore, there is a problem that it is easy to color. In the proposal of SiO ₂ —B ₂ O ₃ —La ₂ O ₃ —TiO ₂ —CaO—BaO-based optical glass (see, for example, Patent Document 6), since CaO is contained in a large amount of 7 to 40% by weight, the meltability is low. It tends to deteriorate, and it becomes difficult to achieve both high refractive index and ensuring devitrification stability.

JP 58-69739 A Japanese Patent Laid-Open No. 58-125637 JP 59-50048 JP JP-A-62-100449 Japanese Patent Laid-Open No. 7-41334 JP 2001-72432 A

  The present invention has been made in view of such conventional problems, and does not include a Pb compound that is likely to have an adverse effect on the environment or the human body, and is excellent in economy and suitable for mass production. An object of the present invention is to provide an optical glass having a high rate of dispersion.

As a result of repeated studies to solve the above problems with respect to the optical glass having a high refractive index and high dispersion, the present inventors have determined that each of SiO ₂ , B ₂ O ₃ , BaO, La ₂ O ₃ , and TiO _{2 has} a glass composition. It has been found that the above-mentioned object can be achieved by blending a specific amount of the present invention, and the present invention has been made. That is, the invention of claim 1 is an optical glass, SiO ₂ : 1 wt% or more and 9.9 wt% or less, B ₂ O ₃ : 10.5 wt% or more and less than 35 wt%, BaO: 13 wt% or more 30 Less than wt%, La ₂ O ₃ : 10 wt% or more and less than 40 wt%, TiO ₂ : 8.9 wt% or more and less than 15 wt%, Nb ₂ O ₅ : 0 to less than 20 wt%, Ta ₂ O ₅ : 0 1.5 wt% or _less, WO 3: less than 0 to 10 _wt%, ZrO 2: less than 0 to 10 wt%, MgO: less than 0 to 10 wt%, CaO: from 0 to 6.8 wt% or less, SrO: less than 0-10 wt%, ZnO: less than 0-20 _{wt%, Li 2 O + Na 2} O + K 2 O: less than 0-2 _wt%, Y ₂ O 3: less than 0-15 _wt%, Gd ₂ O 3: 0~ less than 15 _wt%, Yb ₂ O 3: less than 0 to 10 wt%, _Al 2 O : 0 to less than 5 wt%, and _Sb 2 _O 3: those containing less than 0-1% by weight. And such an optical glass does not contain PbO.

  A second aspect of the invention is the optical glass according to the first aspect of the invention, characterized in that it has an optical constant value having a refractive index (nd) of 1.70 to 1.93 and an Abbe number (νd) of 28 to 45. It is said.

  According to the present invention, it is possible to obtain a high refractive index and high dispersion optical glass that does not impose a burden on the environment because it does not contain highly toxic PbO, and can be mass-produced economically without using an expensive raw material as an essential component.

The optical glass of the present invention contains SiO ₂ , B ₂ O ₃ , BaO, La ₂ O ₃ , TiO ₂ as essential components, and Nb ₂ O ₅ , Ta ₂ O ₅ , WO ₃ , ZrO ₂ , MgO, CaO, SrO. _{, ZnO, Li 2 O, Na} 2 O, is composed K 2 O, a _{Y 2 O 3, Gd 2 O} 3, Al 2 O 3 as an optional component, a refractive index (nd) of at 1.70 to 1.93 The Abbe number (νd) has an optical constant value of 28 to 45.

SiO ₂ and B ₂ O ₃ are skeletal components forming optical glass, SiO ₂ is 1 wt% or more and less than 10 wt% in optical glass, and B ₂ O ₃ is 10 wt% or more and less than 35 wt% in optical glass. Contains each in the range. When the SiO ₂ content is less than 1% by weight, the glass tends to be devitrified and the viscosity at the time of melting of the glass decreases, making it difficult to mold. On the other hand, when it exceeds 10% by weight, it is difficult to make the glass have a high refractive index. Further, it becomes easy to leave an unmelted product at the time of melting. On the other hand, if the content of B ₂ O ₃ is less than 10% by weight, the meltability is deteriorated and the glass tends to be devitrified. On the other hand, if it is 35% by weight or more, it is difficult to make the glass have a high refractive index. It is not preferable because the viscosity at the time decreases and molding becomes difficult.

  BaO has an effect as an excellent flux, has an effect of improving the devitrification stability and increasing the refractive index without coloring the glass, so 13% by weight in the optical glass to obtain a high refractive index glass. More than 30% by weight is contained. If it is less than 13% by weight, the effect of adding BaO is not sufficiently exhibited. On the other hand, if it is more than 30% by weight, chemical durability may be deteriorated.

La ₂ O ₃ improves the chemical durability of the glass and has the effect of increasing the refractive index without coloring the glass. Therefore, in order to obtain a high refractive index glass, it is 10 wt% or more and less than 40 wt% in the optical glass. Contain. If it is less than 10% by weight, the effect of adding La ₂ O ₃ is not sufficiently exhibited. On the other hand, if it is 40% by weight or more, the meltability is deteriorated and devitrification tends to occur.

Since TiO ₂ has an effect of increasing the refractive index and dispersion of the glass, it is contained in the optical glass in an amount of 5 wt% or more and less than 15 wt% in order to obtain a high refractive index and high dispersion glass. If it is less than 5% by weight, the effect of adding TiO ₂ is not sufficiently exhibited, and if it is more than 15% by weight, it tends to be colored, which is not preferable.

In the present invention, in addition to the above essential components, Nb ₂ O ₅ , Ta ₂ O ₅ , WO ₃ , ZrO ₂ , MgO, CaO, SrO, ZnO, Li ₂ O, Na ₂ O, K ₂ O, One or more of Y ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , and Al ₂ O ₃ can be contained within a specific range.

Since Nb ₂ O ₅ has the effect of increasing the refractive index and dispersion of the glass and improving the devitrification stability, the optical glass is within a range that does not hinder the high refractive index and high dispersion optical glass intended by the present invention. It can be contained in a range of less than 20% by weight. On the other hand, if the content is 20% by weight or more, the devitrification stability is lowered, and coloration tends to occur. However, since Nb ₂ O ₅ is expensive, it is preferable that the Nb ₂ O ₅ content be less than 5% by weight considering the economy and the effect on the coloration of the glass.

Ta ₂ O ₅ has the effect of increasing the refractive index of the glass and improving the chemical durability. Therefore, Ta ₂ O ₅ can be contained in the optical glass in an amount of less than 10% by weight as long as the object of the present invention is not hindered. If the content is 10% by weight or more, devitrification stability may be impaired. However, since Ta ₂ O ₅ is expensive, it is preferably less than 2% by weight economically.

WO ₃ has the effect of increasing the refractive index and dispersion of the glass and improving the devitrification stability, and can be contained in the optical glass in an amount of less than 10% by weight within the range not hindering the object of the present invention. If it is 10% by weight or more, the glass may be colored, which is not preferable.

ZrO ₂ has the effect of increasing the refractive index and dispersion without coloring the glass, and can be contained in the optical glass in an amount of less than 10% by weight as long as the object of the present invention is not hindered. If it is 10% by weight or more, the meltability is deteriorated and the devitrification stability may be impaired.

  MgO is useful for adjusting the optical constant of the glass and can be contained in the optical glass in an amount of less than 10% by weight as long as the object of the present invention is not hindered. If it is 10% by weight or more, the meltability may deteriorate, which is not preferable.

  CaO has the effect of reducing the specific gravity of the glass and improving the chemical durability, and can be contained in the optical glass in an amount of less than 7% by weight as long as the object of the present invention is not hindered. If it is 7% by weight or more, the meltability deteriorates and the devitrification stability is impaired, which is not preferable.

  SrO is useful for adjusting the optical constant of the glass and can be contained in the optical glass in an amount of less than 10% by weight as long as the object of the present invention is not hindered. If it is 10% by weight or more, the devitrification stability of the glass may be impaired, which is not preferable.

  ZnO is useful for improving the meltability of the glass, and can be expected to have an effect of reducing the press molding temperature and preventing the press mold from being deteriorated. It can be contained in less than% by weight. If it is 20% by weight or more, the devitrification stability of the glass may be impaired.

Li ₂ O, Na ₂ O and K ₂ O are all useful for improving the meltability, and can be expected to have effects such as lowering the press molding temperature and preventing deterioration of the press mold. As long as there is no hindrance, the total amount of Li ₂ O, Na ₂ O and K ₂ O in the optical glass may be less than 2% by weight. If the total amount is 2% by weight or more, there are problems such as a decrease in chemical durability, an increase in the amount of volatilization during pressing or melting, and a decrease in viscosity at the time of melting, which makes molding difficult.

Y ₂ O ₃ , Gd ₂ O ₃ , and Yb ₂ O ₃ all have the effect of improving the chemical durability of the glass and increasing the refractive index without coloring the glass, which hinders the purpose of the present invention. To the extent that Y ₂ O ₃ is less than 15 wt% in the optical glass, Gd ₂ O ₃ is less than 15 wt% in the optical glass, and Yb ₂ O ₃ is less than 10 wt% in the optical glass. . Above these ranges, the devitrification stability of the glass may be impaired, which is not preferable. _{Y 2 O 3, Gd 2 O} 3, Yb 2 O 3 is often be replaced either with _La 2 _{O 3,} Economically preferably replaced with _La 2 _{O 3.}

Al ₂ O ₃ has an effect of improving the chemical durability of the glass, and can be contained in the optical glass in an amount of less than 5% by weight within the range not hindering the object of the present invention. If it is 5% by weight or more, it is difficult to make the glass have a high refractive index, and an unmelted product tends to remain at the time of melting, which is not preferable.

As described above, the optical glass of the present invention comprises SiO ₂ , B ₂ O ₃ , BaO, La ₂ O ₃ , TiO ₂ as essential components, and includes other optional components, and is configured at the specific ratio. . These components have different functions as components of the optical glass, and when they are configured at the above-mentioned specific ratios, they exhibit their functions and have a high refractive index and high dispersion optical glass of the present invention, particularly a refractive index of 1. A high refractive index and high dispersion optical glass having an Abbe number of 28 to 45 at 70 to 1.93, and further satisfies other requirements for optical glass. These components and their constituent ratios are determined on the basis of a delicate balance in the optical glass, and a satisfactory optical glass is obtained only when these components are within the above range.

Further, a defoaming material may be added in the production of the optical glass. Conventionally known defoaming materials can be used, and there are no particular limitations. For example, Sb ₂ O ₃ and As ₂ O ₃ can be used preferably. The addition amount of the defoaming material is selected within a range that does not hinder the object of the present invention, and is usually about 1% by weight or less in the optical glass.

In addition, for the purpose of clarification, coloring, decoloring and fine adjustment of optical constant values, other components such as known clarifiers, colorants, fluorine compounds, and P ₂ O ₅ are added in appropriate amounts to the glass composition as necessary. be able to.

  The optical glass in the present invention can be produced by a usual method. Typically, raw materials such as oxides, carbonates and nitrates are prepared so as to have a target composition, and melted at 1100 to 1400 ° C. Then, the mixture is stirred and homogenized to remove bubbles, and then cast into a mold.

  Examples of the present invention are shown below, but the present invention is not limited to these examples.

  The corresponding raw materials such as oxide, carbonate, and nitrate are prepared at a predetermined ratio so as to have a target composition ratio, and heated in an electric furnace at 1200 to 1400 ° C. for 1 to 2 hours in a platinum crucible while appropriately stirring. It melt | dissolved, it was cast in the iron mold separately heated previously, and it annealed and made optical glass. Table 1 shows the oxide composition ratio of each component in weight%. The refractive index (nd) and Abbe number (vd) with respect to d line of the obtained optical glass were measured. The results are shown in Tables 1-2.

  As described above, according to the present invention, there is provided a high refractive index and high dispersion optical glass that can be economically mass-produced without burdening the environment in that it does not contain highly toxic PbO and without using an expensive raw material as an essential component. Obtainable.

Claims (2)

In optical glass,
SiO ₂ : 1% by weight or more and 9.9% by weight or less,
B ₂ O ₃ : 10.5 wt% or more and less than 35 wt%,
BaO: 13 wt% or more and less than 30 wt%,
La ₂ O ₃ : 10% by weight or more and less than 40% by weight,
TiO ₂ : 8.9 wt% or more and less than 15 wt%,
Nb ₂ O ₅ : 0 to less than 20% by weight,
Ta ₂ O ₅ : 0 to 1.5% by weight or less,
WO ₃ : 0 to less than 10% by weight,
ZrO ₂ : 0 to less than 10% by weight,
MgO: 0 to less than 10% by weight,
CaO: 0 to 6.8% by weight or less,
SrO: 0 to less than 10% by weight,
ZnO: 0 to less than 20% by weight,
Li ₂ O + Na ₂ O + K ₂ O: 0 to less than 2% by weight,
Y ₂ O ₃ : 0 to less than 15% by weight,
Gd ₂ O ₃ : 0 to less than 15% by weight,
Yb ₂ O ₃ : 0 to less than 10% by weight,
An optical glass comprising Al ₂ O ₃ : 0 to less than 5% by weight and Sb ₂ O ₃ : 0 to less than 1% by weight and containing no PbO.   2. The optical glass according to claim 1, wherein the optical glass has an optical constant value of a refractive index (nd) of 1.70 to 1.93 and an Abbe number (νd) of 28 to 45. 5.