TWI402239B - Optical glass and heated optical glass of oxygen furnace - Google Patents

Description

Adiabatic stove for optical glass and heated optical glass

The present invention relates to optical glass, and more particularly to an optical glass of high refractive index, low glass transition temperature and an anaerobic furnace for heating optical glass.

According to the two important parameters of the optical glass are the refractive index (n _d ) and the glass transition temperature (T _g ). The higher the refractive index of the glass, the stronger the ability to refract incident light, and the glass transition temperature. It is the temperature at which the glassy substance switches between the glass state and the high elastic state. The lower the temperature, the more suitable for the fabrication of optical components.

Conventional high refractive index optical glass is represented by a large amount of a composition containing lead oxide, and is used as a precision press molding because of its excellent glass stability and low glass transition point (T _g ). However, in order to prevent oxidation of the metal mold, the process must be maintained in a reducing atmosphere. Therefore, when lead oxide is contained in the glass component, lead adheres to the surface of the metal mold, and the precision surface of the metal mold cannot be maintained. Moreover, lead oxide is also harmful to the environment.

In order to solve the aforementioned problems, optical glass for press molding having a high refractive index and containing no lead oxide has been extensively developed, and is almost a phosphate-based system. For example, Japanese Patent Laid-Open No. 2003-321245, Japanese Patent Laid-Open No. Hei 8-157231, No. 2003-300751, and the Republic of China Invention No. I305525, No. I315725, etc., all contain P ₂ O ₅ and Nb ₂ O. ₅ and Li ₂ O, Na ₂ O or K ₂ O components. However, the phosphate-based optical glass can solve the problem that the precise surface of the metal mold cannot be maintained when the optical glass containing the lead oxide component is produced. However, the glass transition temperature of the conventional phosphate-based optical glass is not sufficiently low.

The main object of the present invention is to provide an anaerobic furnace for optical glass and heated optical glass, which has a high refractive index and a very low glass transition temperature, and is very suitable for molding and precision molding into optical components.

In order to achieve the foregoing object, the present invention provides an optical glass characterized in that the refractive index (n _d ) is between 1.73 and 1.84, and the glass transition temperature (T _g ) is 361 ° C or less. The range (% by mole) is: 50 to 67% of tin oxide; 20 to 34 mol% of phosphorus pentoxide; 1 to 28 mol% of boron trioxide.

Further, the boron trioxide may be substituted with R ₂ O ₃ (R is ruthenium or gallium).

Further, it contains 64 to 66.7% of tin oxide, 26.3 to 33% of phosphorus pentoxide, and 1 to 7% of boron trioxide, and the glass transition temperature is 264 to 299 °C.

Further, it contains 64 to 66.7% of tin oxide, 32 to 33% of phosphorus pentoxide, and 1-4% of antimony trioxide, and the glass transition temperature is 277 to 300 °C.

Further, it comprises 64 to 66.7% of tin oxide, 32 to 33% of phosphorus pentoxide, and 1 to 4% of gallium trioxide, and the glass transition temperature is 269 to 300 °C.

In addition, the present invention further provides an anaerobic furnace for heating an optical glass, comprising a furnace body for heating an optical glass raw material powder carried by a graphite crucible disposed inside thereof; a tube body connected to the top of the furnace body The side is a quartz tube; a gas cylinder is connected to the tube body for inputting the contained nitrogen gas into the tube body.

Hereinafter, the second preferred embodiment of the present invention will be further described in detail with reference to the drawings. First, the optical glass (tin phosphate glass) of a preferred embodiment of the present invention is mainly composed of tin oxide (SnO). And phosphorus pentoxide (P ₂ O ₅ ) and boron trioxide (B ₂ O ₃ ) and other components, and the molar percentage of each of the components is as follows:

Tin oxide 50~67%;

Phosphorus pentoxide 20 to 34 mol%;

Boron trioxide 1 to 28 mol%.

In the production of the optical glass of the present invention, the raw materials are prepared and mixed according to the composition of the prior composition, and the uniformly mixed powder is loaded into a graphite crucible, and heated at a constant temperature of about 900 ° C (depending on the glass composition) for 30 minutes. The components can be completely melted and homogenized, and then the molten glass liquid is poured onto a copper plate, and after annealing at 260 ° C to 360 ° C for 5 hours, it is cooled to room temperature. The process for extracting the heated glass component is carried out in an anaerobic furnace 10 as shown in FIG. 1 for melting the glass component in an anaerobic environment to avoid oxidation. The anaerobic furnace 10 comprises a furnace body. 12. A tube body 14 and a gas cylinder 16, wherein the graphite crucible is heated in the furnace body 12. The tube body 14 is a quartz tube connected to the top side of the furnace body 12 and sealed by a refractory cotton. The tube 14 is connected and supplied with nitrogen.

Therefore, the glass characteristics of the optical glass of the present invention can be clearly illustrated by the respective embodiments. As can be seen from the respective examples of Table 1, the refractive index of the optical glass of the present invention can reach 1.84, and the glass transition temperature (T _g ) is 361 ° C or less. Among them, the preferred composition ratio range is: 64 to 66.7% of tin oxide, 26.3 to 33% of phosphorus pentoxide, and 1 to 7% of boron trioxide. In this range, the glass transition temperature is 264 to 299 ° C. Below 300 ° C, compared to other high refractive index glass, it has a very low glass transition temperature, so it is suitable for molding processes such as molded glass preforms and precision molded optical components.

Furthermore, in the glass component of the optical glass of the present invention, boron trioxide may also be substituted by R ₂ O ₃ (R is gallium or germanium), as shown in Table 2, which is tin oxide-phosphorus pentoxide-antimony trioxide. (Sb ₂ O ₃ ), the preferred composition ratio range: 64 to 66.7% of tin oxide, 32 to 33% of phosphorus pentoxide, 1-4% of antimony trioxide, glass transition temperature of 277 to 300 ° C It is also below 300 °C.

As shown in Table 3, it is tin oxide-phosphorus pentoxide-dia gallium trioxide (Ga ₂ O ₃ ), and its preferred composition ratio ranges from 64 to 66.7% of tin oxide, and 32 to 33% of pentoxide. Phosphorus, 1-4% of gallium trioxide, glass transition temperature of 269 ~ 300 ° C, also below 300 ° C.

As can be seen from the above, the optical glass and the anodic stove for heating the optical glass provided by the present invention, the optical glass is a phosphate-based glass, and the refractive index of each component can be appropriately adjusted to be 1.73 to 1.84, which is a high refractive index. Glass, and the glass transition temperature (T _g ) is 361 ° C or less. The glass transition temperature of the preferred component ratio range is more than 300 ° C. The glass transition temperature is extremely low, which is obviously higher than the conventional high refractive index glass. It is suitable for molding process and precision forming into optical components.

10. . . Anaerobic stove

12. . . Furnace body

14. . . Tube body

16. . . Gas cylinder

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of an anaerobic furnace for heating optical glass in a preferred embodiment of the present invention.

10. . . Anaerobic stove

12. . . Furnace body

14. . . Tube body

16. . . Gas cylinder

Claims (7)

An optical glass characterized in that the refractive index (n _d ) is between 1.73 and 1.84, the glass transition temperature (T _g ) is 361 ° C or less, and the composition range of the main component (percent of mole) is: 50 to 67%. Tin oxide (SnO); 20 to 34 mol% of phosphorus pentoxide (P ₂ O ₅ ); and 1 to 28 mol% of boron trioxide (B ₂ O ₃ ). The optical glass of claim 1, wherein the boron trioxide is substituted by R ₂ O ₃ (R is ruthenium or gallium). The optical glass according to claim 1, wherein preferably, it comprises 64 to 66.7% of tin oxide, 26.3 to 33% of phosphorus pentoxide, and 1 to 7% of boron trioxide. The glass transition temperature is 264 to 299 °C. The optical glass according to claim 2, wherein preferably, it comprises 64 to 66.7% of tin oxide, 32 to 33% of phosphorus pentoxide, and 1 to 4% of antimony trioxide. The glass transition temperature is 277 to 300 °C. The optical glass according to claim 2, wherein preferably, it comprises 64 to 66.7% of tin oxide, 32 to 33% of phosphorus pentoxide, and 1 to 4% of gallium trioxide. The glass transition temperature is 269 to 300 °C. An optical glass according to any one of claims 1 to 5, which is used for an optical element. An anaerobic furnace for heating an optical glass according to any one of claims 1 to 5, comprising: a furnace body for heating the optical layer carried by one of the graphite crucibles disposed therein a glass raw material powder; a tube body connected to the top side of the furnace body, a quartz tube; and a gas cylinder connected to the tube body for inputting the accommodated nitrogen gas into the tube body.