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Glass composition

A glass composition and glass transition technology, applied in glass molding, glass manufacturing equipment, instruments, etc., can solve problems such as unsuitable optical glass, large Abbe number, high devitrification temperature, etc.

Inactive Publication Date: 2008-04-16
OHARA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this glass has a very high devitrification temperature or a very large Abbe number, therefore, this glass is not suitable for the optical glass for compression molding for the purpose of the present invention

Method used

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Examples

Experimental program
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Embodiment

[0131] Examples No.1 to No.60 of the present invention shown in Tables 1 to 24 and as containing SiO 2 , B 2 o 3 , La 2 o 3 and Li 2 Comparative Examples No.A to No.F of glasses of known glasses of O, and optical constants (nd, vd), glass transition temperature Tg, yield point At, coefficient of linear thermal expansion α, devitrification temperature, and specific gravity.

[0132] In order to manufacture the glasses of Examples No. 1 to No. 60, common raw materials for optical glass including oxides, carbonates and nitrates were weighed and mixed to achieve the respective examples shown in Tables 1 to 24 composition ratio. The raw material is placed in a platinum crucible and melted at a temperature ranging from 1200°C to 1400°C for two to four hours depending on the melting properties of the composition. After clarifying and stirring the melt for homogenization, the melt is cast into a mold and tempered, thereby easily providing a homogeneous glass.

[0133] According...

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Abstract

There is provided a glass composition having a devitrification temperature of 1000 or below, a glass transformation temperature (Tg) of 535 or below and a specific gravity within a range from 3 to 4. The glass composition has a refractive index (nd) within a range from 1.60 to 1.75 and an Abbe number ( d) within a range from 50 to 60.

Description

technical field [0001] The present invention relates to a glass composition, although it contains SiO 2 , B 2 o 3 , La 2 o 3 and Li 2 O, still has a low glass transition temperature (Tg) and low devitrification temperature and is suitable for compression molding. Background technique [0002] It is a recent general trend to produce lightweight and compact optical elements for portable devices such as digital cameras and mobile phones using aspheric mirrors produced by compression molding. If one tries to produce the aspheric mirror with conventional grinding and polishing, it requires many expensive and complicated processes. Therefore, a method is recently used according to which a preform obtained by dropping molten glass or grinding and polishing a glass sheet is directly formed into a lens by using a high-precision processing mold. Since it is not necessary to grind and polish the resulting lens by this method, the lens can be manufactured at low cost and in a sho...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C03C3/068G02B1/00
CPCC03B19/1055C03B7/12C03C3/068
Inventor 清水晃治
Owner OHARA
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