TW200932697A - Optical glass, and preform for fine press molding and optical element each comprising the same - Google Patents

Abstract

Disclosed is an optical glass which comprises 15 to 30% of B2O3, 2 to 8% of SiO2, 15 to 30% of La2O3, 15 to 30% of Gd2O3, 20 to 30% of ZnO, 0.1 to 2% of Li2O, 0.1 to 6% of ZrO2 and 0.1 to 6% of Ta2O5 as essential components, and optionally further comprises 0 to 6% of WO3, wherein all of the contents of the components are expressed in terms of the oxide contents by mass. The optical glass has a total content of Ta2O5, ZrO2 and WO3 of 0.2 to 9%, a refractive index (nd) of 1.77 to 1.78, an Abbe's number (?d) of 46 to 48, and a glass transition temperature (Tg) of 600 DEG C or lower. The optical glass has high-refractive and low-scattering optical properties, has a low molding temperature, is less likely to devitrify, and has excellent molding resistance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass field having a high refractive index and a low dispersibility, a preform for precision press forming using the same, and an optical element. [Prior Art] „ In recent years, the demand for lightweight and miniaturized optical lines has increased due to the popularity of digital cameras and cameras with high-definition materials. In response to these requirements, The use of high-performance glass non-balloon® lenses is becoming the mainstream, especially in the use of non-5 facet lenses with large apertures that exhibit high refractive index and low dispersion characteristics. In addition, as a method of manufacturing an aspherical lens, a precision punching method which does not require a polishing step is becoming mainstream in terms of productivity and manufacturing cost. As a glass exhibiting high refractive index and low dispersion characteristics Previously known as B2〇3, La2〇3 as the main component of the glass. However, these emphasis are on 〇 & improve chemical durability, thermal devitrification and thermoformability, not fully considered heat High-temperature formability of a glass preform preform (hereinafter also referred to simply as a preform) necessary for press forming, particularly a high refractive index and low dispersion optical such as refractive index nd > 1.77, Abbe number Vd > 46 . The glass is not suitable for the obstruction of the preform by the precision punching of the aspherical lens. The reason is that 'generally' the glass has a higher liquidus temperature or lower (four) To produce high-precision preforms. In the fine and stamping process, the lower the press forming temperature, the more durable the mold is, the shorter the 'forming cycle' is, and the higher the forming temperature is, the lower the forming temperature is 136735.doc 200932697 Optical In the case of the optical glass of the prior art, especially for the optical glass for precision press forming, if the refractive index nd > 1.77, Abbe number ~ > 46, the liquidus temperature will greatly exceed 100 generations. The thermal stability is also deteriorated, and the preform is easily devitrified during molding. Therefore, mass production is not good, and it is difficult to precisely and uniformly manufacture a glass preform for press forming. - To solve the above problems, in the patent literature 1 discloses a glass having φ which is mainly composed of B2〇3-Si〇2-La2〇3_Gd2〇3-Zn0-Li2〇_Zr〇2, and d 75 1,85, Vd=40 to 55. However, in the optical lens or the like of Patent Document 1, it contributes to reduction The total content of the U20_zn0, which is a component of the shape temperature, is less than 12 to 24 m%, so that there is a problem that the molding temperature is high. Here, in the optical lens of Patent Document 1, if it is converted by mass percentage, The total content of Ta^5, Zr〇2, and w〇3 exceeds 9 mass%. Ta2^ is a rare resource and is difficult to obtain, and is an expensive composition. Therefore, there are the following problems: I7 has more Ding&2 〇5, the price of the finished optical lens is higher, and if the content of Zr〇2 is large, there is a problem that the devitrification temperature becomes high. Causes coloring problems. However, if the content of the above composition is too small, there is a problem that the refractive index is lowered. Further, Patent Document 2 discloses the following glass, which is B2〇3_

La203-Zn〇-Li2〇 is an essential component, nd=1 66M 77, 々=43 to 55, and the deformation point is 620 ° C or lower, and exhibits a high refractive index and a low dispersion property. Further, Patent Document 3 discloses a glass having Be" La203-Gd2〇3_Zn〇_Li2〇 as an essential component, ~=1 68~! 8, 136735.doc 200932697 vd=44~53, deformation point In the optical glass of Patent Document 2 and Patent Document 3, liquid phase temperature and warm molding are not disclosed. [Patent Document 1] Japanese Patent Laid-Open No. 2003-201143 [Patent Document 2] Japanese Patent No. 345 8461. [Patent Document 3] Japanese Patent No. 3548462. [Disclosure] [Problems to be Solved by the Invention] An object of the present invention is to provide an optical glass. It has high optical properties of high refractive index and low dispersibility, and has a low forming temperature, is not easily devitrified, and is excellent in formability. [Technical means for solving the problem] The optical glass of the present invention is characterized by an oxide-based quality. Percentage meter 'containing B2〇3: 15~30%, SiO2: 2~8%, La203: 15~30〇/〇, Gd203: 15~30〇/〇, ZnO: 20~30%, Li20: ❹ 0· 1 〜2°/〇, Zr〇2 : 〇.1 ～6%, Ta205: 0.1 ～6./. The essential component, and contains W03: 〇~6% as an optional component, Ta2〇5+ZrC)2+w〇3 has a yttrium of 0.2~9.0〇/〇, and the refractive index (^ is j 774 78, Abbe number) (...) is 46 to 48' and the glass transition temperature (Tg) g 6 〇〇〇 c or less. The preform for press forming of the present invention is characterized by comprising the following optical glass in which the oxidation is performed The mass percentage of the material standard, including B2〇3: 15~30%, SiO2: 2~8%, La203: 15~30%, Gd203: 15~30〇/〇, ZnO: 20~30%, Li20: 0.1 ~2%, Zr02: 〇'1~6%, Ta205: 0·1~6% as an essential component, and containing w〇3: 136735.doc 200932697 0~6% as an optional component, Ta205+Zr02+W〇3 The content is 0, 2 to 9.0%, the refractive index (nd) is 1.77 to 1.78, the Abbe number (Vd) is 46 to 48, and the glass transition temperature (Tg) is 600 ° C or less.

The optical glass of the present invention (hereinafter referred to as the present glass) has a high refractive index, a refractive index nd=1.77 to 1.78, a low dispersion, an Abbe number vd=46 to 48, and a glass transition temperature (Tg) of 600. Below °C. Further, since the present glass satisfies the relationship of the mass ratio of La203/(La203 + Gd203) of 〇.4 to 0.6, the liquid phase temperature (TL) is 1000 °C or less. [Embodiment] The reason for setting the range of each component of the present glass will be described below. In the following description, the content is a content based on the total amount of the oxide contained in the composition. In the present glass, B2〇3 is a component which forms a glass backbone and lowers the liquidus temperature, and is an essential component. In the present glass, the content of Βζ03 is 15 to 30% by weight: % (hereinafter, mass % is abbreviated as %). If the content of Β2〇3 is less than 15. 〆❶, it is difficult to vitrify' or the liquidus temperature TL will become high. In order to lower the liquidus temperature TL, the content of B2〇3 is preferably 17% or more and 18% or more. If the content of B2〇3 is 19% or more and the Abbe number can be increased to 46~48, it is better that the content of B2〇3 is better than 'the liquidus temperature is lowered, and the other is in the glass, if B2 When the content of cerium 3 exceeds 30%, there is a possibility that the refractive index is lowered or the chemical durability such as water resistance is lowered. In the present glass, the content of B2G3 is preferably 27% or less, and when the refractive index nd is to be increased to m_78, the content of B2〇3 is preferably below. 136735.doc 200932697 In the present glass, 'Si〇2 is the same as Βζ〇3 to form a glass backbone, which stabilizes the glass or suppresses the devitrification component at the time of high-temperature molding, and is a necessary component. In the present glass, the content of Si〇2 is 2 to 8%. When the content of Si〇2 exceeds 8°/〇', the molding temperature becomes too high, or the refractive index nd becomes too low. The content of Sl〇2 is more preferably 7% or less, and the content of SiO 2 is further preferably 6% or less. On the other hand, when it is intended to suppress devitrification during high-temperature forming, or to adjust viscosity, Si〇2 The content is preferably 3% or more. © In the present glass, 'ZnO is a component which stabilizes glass and lowers the molding temperature or melting temperature' and is an essential component. In the present glass, the content of Zn〇 is 20 to 30%. Further, the content of Zn 〇 is expressed as % to 4 〇 Mo 〇 / ❶. If the content of B> is less than 2%, the glass becomes unstable and the chemical properties are lowered. On the other hand, in the present glass, if the content of Zn〇 exceeds 303⁄4 ', the stability of the glass is deteriorated, and the devitrification is likely to occur. The better content of zn〇 is 26. / 〇 The following ' ZnO content is better than 25%. In the present glass, La2〇3 is a φ component which increases the refractive index nd and improves chemical durability, and is an essential component. In the present glass, the content of La203 is 15 to 30%. If the content of La2〇3 is less than 15%, the refractive index nd becomes too low. The content of La2〇3 is preferably 19% or more, and the content of La2〇3 is more preferably 20% or more. On the other hand, when the content of La203 exceeds 30%, it is difficult to vitrify, the molding temperature becomes high, or the liquidus temperature TL becomes high.

The content of LajO3 is preferably 26% or less, and the content of La203 is more preferably 25% or less. In the present glass, 'Gd2〇3 is a component which increases the refractive index nd and improves the chemical durability as in the case of La203, and is an essential component. In this glass, Gd203 has a content of 136735.doc •10- 200932697 of 15~30°/. If the content of Gd203 is less than 15%, the refractive index ~ will decrease. The content of Gd2〇3 is preferably 19% or more, and the content of Gd203 is more preferably 20% or more. On the other hand, when the content of Gd2〇3 exceeds 30%, it is difficult to vitrify, the molding temperature becomes high, or the liquidus temperature T1 becomes high.

The content of Gd2〇3 is preferably 26% or less, and the content of Gd203 is more preferably 25% or less.

In the present glass, 'optimizing the ratio of La2〇3 to Gd2〇3' has an effect of greatly reducing the liquid phase temperature (TL). In particular, by satisfying the relationship that the mass ratio of La203/(La203 + Gd203) is 〇·4 to 〇.6, the liquidus temperature (TL) becomes 10 〇〇 ° C or less. In the present glass, the 'LhO system stabilizes the glass', which is a component which lowers the molding temperature and the melting temperature, and is an essential component. In the present glass, ["the content of bismuth is 0.1 to 2%. If the content of LhO is less than 〇·1%, the molding temperature or the melting temperature becomes too high. The content of LhO is preferably 0·2. When the content of Li2 is more than 2%, the content of the content of U2 is more than 0.3%. On the other hand, if the content of Li2 is more than 2%, the devitrification is likely to occur, and the chemical durability is lowered or the volatilization of the components at the time of melting is increased. The content of LhO is preferably less than or equal to or less than 1.0%, and the content of U2 is more preferably 1.0% or less. Further, the content of Li2 is 0.1 to 8 moles per liter %. The Ding 〇5 series stabilizes the glass, raises the refractive index ～, and suppresses the devitrification component at the time of high-temperature molding, and is an essential component. In the present glass, the content of Ta 2 〇 5 is 01 to 6%. If the content of 5 is less than 〇, the refractive index becomes too low, or the liquidus temperature T1 becomes too high. The content is preferably 1% or more, and the content of Ta2〇5 is more preferably 2%. The above 2. 5 136735.doc 11 200932697 On the other hand, if the content of Ta2〇5 exceeds 6%, the forming temperature becomes excessive, or the Abbe number vd becomes too small. Ta2〇 The content of 5 is preferably 5·5°/❶ or less, and the content of Ta2〇5 is more preferably 5% or less.

In the present glass, Zr〇2 stabilizes the glass, raises the refractive index nd, and suppresses devitrification components at the time of high-temperature molding, and is an essential component. In the present glass, the content of Zr〇2 is. When the content of Zr〇2 exceeds 6%, the forming temperature becomes too high, or the Abbe number Vd becomes too small. The content of Zr〇2 is preferably 5.5% or less, and the content of Zr〇2 is more preferably 5% or less. On the other hand, in order to obtain the effect of addition, the content of Zr〇2 is more preferably 1% or more, and the content of Zr〇2 is more preferably 2% or more. In the present glass, WO3 is not an essential component, but it stabilizes the glass, raises the refractive index nd' and suppresses the devitrification component at the time of high-temperature molding, and may contain 〇 to 6%. When the content of W〇3 exceeds 6%, the forming temperature becomes high, and the Abbe number u d becomes small. The content of W〇3 is preferably 5% or less. Here, in the present glass, the total content of Ta2〇5, Zr〇2, and w〇3 (hereinafter also abbreviated as Ta+Zr+W) is 〇·2 to 9 mass%. Preferably, Ding + w is 8.5% or less, and more preferably 8 % or less. μ is a rare resource and is difficult to obtain 'and is an expensive component. Therefore, if it contains a large amount (10), it means that the price of the completed optical lens or the like is large, and the devitrification temperature is increased by one. If the content of W〇3 is large, mTa2〇 is caused. 5. If the total content of ton and w〇3 is less than 〇, then there is a decrease in the refractive index 因此' so the total content is 〇2% or more. Further, in the case where the total content of 'Ta2〇5, Zr〇2, and W〇3 exceeds 9%, the refractive index is lower than the case where the total content of the spots is 9% or less. Therefore, for 136735.doc •12· 200932697, the 'refractive index' must contain quite a lot of La203 and Gd203. In the present glass, Nb2〇5 is not an essential component, but may be contained in an amount of 0 to 6% in order to stabilize the glass, increase the refractive index nd, and suppress devitrification during high-temperature molding. If the content of ^^2... exceeds 6%, the Abbe number... becomes too small, or the transmittance is lowered. The content of Nth is preferably 5% or less. In the present glass, Y2〇3 and YhO3 are all non-essential components. However, in order to increase the refractive index nd and suppress devitrification during high-temperature molding, 〇~6% may be contained. If the ❹

When the content is more than 6%, the glass becomes unstable and the molding temperature becomes too high. The content of Y2〇3 and Yb2〇3 is preferably 5% or less. In the present glass, Al2〇3 is not an essential component, but in order to stabilize the glass, the refractive index is adjusted to be equal to or equal to, and G to 6% e may be contained in an amount exceeding 63° from the content of 03. , then the Abbe number Vd becomes too low. The content of 八12〇3 is more preferably 5% or less. In the present glass, BaO is not an essential component, but in order to stabilize the glass, the Abbe number vd is increased, or the molding temperature is lowered, the specific gravity is decreased, and the content of the green genus is more than 6%. The glass becomes unstable, or the refractive index nd becomes low. The content of Ba〇 is better (4) below. Further, for the purpose of purification or the like, the present glass may contain 〇2% of Sb2〇3 0. The glass essentially contains the above-mentioned components. The total content of these components is preferably 95% or more. Other ingredients may also be included within the scope not to the object of the present invention. When the above other ingredients are contained, the total content of the components such as lanthanum is preferably 5%. Further, if expressed in terms of mass percentage, the content of the other components is 5 mass% or less. 136735.doc -13- 200932697 Further, in order to further stabilize the glass, adjust the refractive index nd, adjust the specific gravity, lower the melting temperature, etc., the total content may be 0 to 5 ° /. The components of Na2〇, κ20, Rb20 or Cs20. When the content of each component of Na2?, K2?, RhO or CS? is more than 5%, the glass becomes unstable, the refractive index ? becomes low, the hardness becomes small, or the chemical durability is lowered. Further, it is preferable that any of Na2〇, K20, Rb20 or Cs20 is contained in the case where hardness or chemical durability is emphasized. In the present glass, any component other than the above may be selected according to each desired characteristic. For example, when a high refractive index to a low glass transition point is emphasized, Sn02 of 〇~4% may be contained. Similarly, in the case where the high refractive index is emphasized, it is also possible to contain 0 to 6% of Te〇2 and/or Bi2〇3 alone or in total. If the content of Te〇2 and/or 2〇3 exceeds 6%, the glass becomes unstable and the transmittance is remarkably lowered. However, when it is desired to increase the Abbe number 1; £1, it is preferred that none of Te〇2 or Bi2〇3 is contained. In the present glass, in order to reduce the burden on the environment, it is preferred that substantially no one of PbO, Tl〇2, F, and As2〇3 is contained. When fluorine is contained, the coefficient of thermal expansion increases, and the mold release property and moldability are adversely affected. In addition, since the components are easily volatilized, the composition of the optical glass tends to become uneven, and the mold such as the release film is obtained. Problems such as reduced durability. In the present glass, it is preferable to contain FezO3' for the reason of preventing coloring or the like, but it is usually inevitably mixed into the Bushan factory from the raw material. Even in this case, the content of FeW3 in the glass is preferably 〇. 〇〇〇 1% to 136735.doc •14- 200932697. For the optical properties of the present glass, the refractive index... is ^78. When the refractive index nd is 1.77 or more, it is suitable for downsizing and thinning of the lens, which is preferable. On the other hand, if the refractive index ^ of the present glass exceeds 178, the Abbe number becomes too small and adversely affects other thermophysical properties - and thus is not preferable. The Abbe number of the glass (| is 46 to 48. The liquidus temperature of the glass is preferably 1 〇〇〇. (: The following. If the liquidus temperature TL exceeds 100 (TC, it is formed at a high temperature) The molded article is easily devitrified. Further, when the liquidus temperature TL is maintained at a certain temperature, it is defined as the maximum temperature at which no crystal solidified material is generated from the glass melt. The glass transition fiTg of the glass is 600 ° C or less. When the glass transition point \ is 6 〇〇 1 or less, the "temperature" can be lowered, and the durability of the protective film or the like formed on the surface of the mold is improved. Therefore, it is more preferable that the glass transition point is 580 〇C or less. After the glass is melted in a dissolution tank or the like in which the discharge nozzle is attached, the G 35 molten glass is dropped from the discharge nozzle and cooled, whereby a preform for molding having a specific quality can be formed. The part is placed in a mold for precision press forming (a representative structure consists of an upper mold, a lower mold, and a mold body), and after being heated to a deformable temperature, it is pressurized, cooled, and taken out. Forming an optical component. 7 as formed by the present glass Examples of the optical element include various types of lenses for digital still cameras, digital cameras, and mobile phones with cameras. In particular, aspherical lenses are preferred. [Embodiment] 136735.doc 200932697 Hereinafter, according to an embodiment ( Specific examples of the present invention are described in Examples 1 to 6, Examples 9 to 13) and Comparative Examples (Examples 7 to 8), but the present invention is not limited to the above aspects. Example 8 is Patent Document 1 Example 3 6. As a raw material preparation method, the following raw materials were blended in such a manner as to obtain a glass of the composition shown in the table, and placed in a platinum crucible at a temperature of 11 Torr to 13 Torr: After melting for 1 hour, the molten glass was homogenized by stirring with a platinum stirrer for 5 hours. After the homogenized molten glass was discharged and formed into a plate shape, it was kept at a temperature of Tg+1 〇C for 4 hours. Thereafter, it was gradually cooled to room temperature at a cooling rate of _60 〇c / h. Further, the portion indicated by "_" in the table indicates that the component is absent. As a raw material, boron oxide, aluminum oxide, lithium carbonate, and Zirconia, zinc oxide, cesium carbonate and lanthanum oxide A special grade reagent manufactured by Kanto Chemical Co., Ltd. Oxidation, Oxidation, and Oxidation Systems use a reagent with a purity of 99.9% manufactured by Shin-Etsu Chemical Co., Ltd. Oxidation group, cerium oxide, oxidized crane, cerium oxide, oxidizing mirror, and lanthanum oxide system. A reagent prepared by the High Purity Chemical Research Institute with a purity of 99.9% or more. For the obtained glass, the refractive index nd at a wavelength of 587·6 nm (d line) and the refractive index at a wavelength of 656.3 nm (C line) are measured. η., the refractive index ηρ at the wavelength of 486 1 nm (F line), the Abbe number..., the glass transition point (unit: C), the deformation point At (unit: 〇), the liquidus temperature Tl (unit: It) and the specific gravity d. The measurement methods of these are described below. Thermal Characteristics (Glass Transfer Point Tg): Using a Thermomechanical Analysis Device (Mac)

Science company, trade name: DILATOMETER 5000), measured at a heating rate of 5 ° C / min. The diameter of the sample is 136735.doc •16- 200932697. Abbe Vd): A sample having a rectangular parallelepiped shape of 20 mm on one side and 10 mm in thickness was measured using a precision refractometer (manufactured by Kalnew Optics Co., Ltd., trade name: KPR_2). The refractive index ^ was measured for a sample obtained at a slow cooling rate of ° C / h. Furthermore, the Abbe number Vd is obtained by the calculation formula {(nd_1)/(nF_nc)}.

Liquid phase temperature TL: A sample of a cube shape processed to a side of 1 〇 mm was placed in a platinum vessel and allowed to stand in an electric furnace set to a fixed temperature for 1 hour, and then taken out by a 1× optical microscope. The sample taken out was observed, and the highest temperature at which precipitation of crystals was not observed was set as the liquidus temperature TL.

Hereinafter, the measurement and the calculation result are shown in the table. Table 3 and Table 3 show the composition of the glass of the present invention and the comparative examples in the examples of the present invention. Tables 2 and 4 show the examples of the present invention and the glass in the comparative examples by mass percentage. Component. Further, since the sample of Example 7 was devitrified, the measurement of the refractive index or the like was not carried out. This position is indicated by "_".

136735.doc 17· 200932697 [Table 2]

Ex. 1 ex. 2 ex. 3 ex. 4 ex. 5 ex. 6 ex. 7 ex. 8 B2O3 21.08 20.73 21.66 22.32 20.78 20.68 20.04 22.11 Si02 5.19 5.98 4.86 3.66 6.00 5.97 4,28 6,36 Li20 0.78 0.78 0.79 0.79 0.78 0.78 0.00 1.38 ZnO 20.91 20.92 21.16 21.13 20.97 20.87 28,45 12.92 La2〇3 22.31 22.32 22.58 22.54 24.51 20.14 22.36 25.87 Gd2〇3 22.65 22.19 22.44 22.41 19.87 24.50 24.88 21.59 Zr02 3.11 3.11 3.96 3,15 3.12 3.11 0.00 2.45 Ta2 〇5 3.96 3.96 2.55 4.00 3.97 3.95 0.00 7.32 La+Gd 44.96 44.51 45.02 44.96 44.38 44.64 47.24 47.46 La/(La+ Gd) 0.50 0.50 0.50 0.50 0.55 0.45 0.47 0.55 Ta+Zr+ W 7.07 7.08 6.51 7,15 7.09 7.06 0.00 9.77 [ Table 3] ex. 9 ex. 10 ex. 11 ex. 12 ex. 13 B2O3 35.2 35.2 34.9 35.4 35.0 Si02 11.8 11.8 11.5 11.8 11.6 Li20 3.1 3.1 2.4 3.1 2.5 ZnO 30.4 30.4 31.4 30.5 31.5 La2〇3 8.8 7.3 8.0 8.1 8.1 Gd2〇3 6.4 7.9 7.3 7.3 7.4 Zr02 2,5 3.0 2.0 2.3 3.0 Ta2〇5 1.1 1.1 0.8 1.4 1.1 w〇3 0.8 0.5 1.5 0.2 0.0 La+Gd 15.2 15.2 15.3 15.4 15.5 La/(La+Gd) 0.58 0.48 0.52 0.53 0.52 Ta+Zr+W 4.4 4.6 4.3 3.9 4.1 n<3 1.77309 1.77180 1.77354 1.77153 1.77277 vd 46.66 46.84 46.15 46.99 47.10 T/c 574 579 579 578 579 Tl/°C 980 980 960 970 990

Ta+Zr+ W 4.09 4.05 4.48 4.15 4.05 4.05 0.00 4.6 nd 1.77346 1.77066 1.77232 1.77492 1.77155 1.77023 - 1.76861 vd 47.20 47.11 47.27 47.06 47.07 47.09 - 47.94 T/c 575 575 574 573 575 578 - 570 TJ°C 990 980 1000 1000 990 990 - 1000 18- 136735.doc 200932697 [Table 4] ex. 9 ex. 10 ex. 11 ex. 12 ex. 13 B203 20.7 20.3 20.6 20.5 Si〇2 6.0 ~53 5.8 5.9 5.8 L12O 0.8 0.8 —---- 0.6 0.8 0.6 Z.nU 20.8 20.8 21.3 20.8 21.6 La2〇3 24.2 ~T9j 21.9 22.0 22.1 Gd2〇3 19.6 L__24:〇22.2 22.1 22.4 Zr〇2 2.6 —3Γ 2.1 2.4 ϊϊ Ta205 3.9 2.8 5.1 3.9 WO3 1.5 0.9 3.0 0.3 〇. 〇La+Gd 43.8 44.1 44.1 44.5 La/(La+Gd) 0.55 0.45 0.50 0.50 0.50 Ta+Zrf-W 8.0 7.9 7.9 7.8 7.0 ❹ - Although the invention has been described in detail with reference to specific aspects, the It is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention. Further, the present application is based on a Japanese patent application filed on Dec. 6, 2009, the entire content of Moreover, all of the reference frames cited herein are incorporated by reference in their entirety herein. [Industrial Applicability] The present invention can provide optical glass suitable for use as an optical component such as a digital camera. 136735.doc •19·

Claims (1)

200932697 X. Application for Patent Park: 1. An optical glass, expressed as a percentage by mass of oxide, containing B2O3: 15~30%, Si02: 2-8% 'La2〇3: 15~30%, Gd203: 15~30%, ZnO: 20-3 0% 'Li2〇: 0.1-2% ' ❿ Zr02 : 〇·ΐ~6%, Ta2〇5 : 〇.1~6% as an essential component, and contains W〇3 : 〇~6% as an optional component, the content of Ta205+Zr02+W03 is 〇·2~9.0%, and the refractive index (nd) is 1.77~1.78, the Abbe number (Vd) is 46~48, and the glass transition temperature ( Tg) is below 60 CTC. 2. The optical glass of claim 1, which contains Al2〇3: 0-6% 'Ya〇3: 0-6% 'Yb203: 0-6% ' BaO: 〇~6%, : 〇~2%, Can 2〇5 : 0~6% as an optional component, and in terms of mass percentage, must be a total of I 9 5 % or more. 136735.doc 200932697 3. The optical glass of claim 1 or 2, wherein substantially no PbO, Tl 〇 2, F, AS 2 O 3 are absent. 4. The optical glass of claim 1, wherein the mass ratio of La2〇3/(La2〇3 + Gd203) is 〇.4~〇 6 , 7 υ·6, and the liquidus temperature (Tl) is 〇〇〇. |0 or less. An optical breakage of a preform for press forming. It contains any of the claims 1 It is obtained by shaping the object as claimed. Light of any one of 4 136735.doc 200932697 VII. Designated representative 囷: (1) The representative representative of the case is: (none) (2) The symbol of the symbol of the representative figure is simple: Φ 8. If there is a chemical formula in this case, Please reveal the chemical formula that best shows the characteristics of the invention: (none) 136735.doc