Process for the production of glass molded article, optical element produced by the process, and method of treating glass

Inactive Publication Date: 2005-01-20
HOYA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

Under the circumstances, it is an object of the present invention to provide a process for efficiently producing a transparent glass molded article, particularly a precision press-molde

Problems solved by technology

And, it is difficult to control the color degree by merely heating the glass, and the color degree i

Method used

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  • Process for the production of glass molded article, optical element produced by the process, and method of treating glass
  • Process for the production of glass molded article, optical element produced by the process, and method of treating glass
  • Process for the production of glass molded article, optical element produced by the process, and method of treating glass

Examples

Experimental program
Comparison scheme
Effect test

Example

Example 1

A glass having a composition 1 shown in Table 1 (22.8 mol % of P2O5, 15.2 mol % of WO3, 15.9 mol % of Nb2O5, 10.1 mol % of Li2O, 9.7 mol % of Na2O, 2.5 mol % of K2O, 16.2 mol % of BaO and 7.6 mol % of B2O3) was prepared by melting at 1,100° C. After gradually cooled, the glass had a yellowish color. The glass had properties as shown in Table 1. The glass was formed into a sheet having a thickness of 2 mm by cold working, and the glass having a sheet form was heat-treated in a nitrogen gas atmosphere at 560° C. As the time period of the heat treatment increased, circumferential areas of the glass began to turn blackish purple and the entire glass was colored in several tens minutes. FIG. 1 shows a change of a transmittance spectrum with the passage of the heat treatment time. As shown in FIG. 1, the minimum transmittance was controlled to be 62% by controlling the heat treatment time period.

Glasses having compositions 2 to 28 shown in Tables 1 to 6 were successfully colo...

Example

Example 2

The colored glass obtained by heat treatment in a nitrogen gas atmosphere for 36 minutes in Example 1 was heat-treated under atmosphere of air at 480° C. FIG. 2 shows a change of a transmittance spectrum in the heat treatment under atmosphere of air. With an increase in the time period of the heat treatment, the glass colored in blackish purple came to be lighter in color. After 4 hours, the glass came to be nearly colorless.

The glasses having compositions 2 to 28, which were treated for coloring in Example 1, were similarly heat-treated under atmosphere of air, whereby the color degrees of the glasses were decreased and the glasses were decolored and rendered transparent. After the heat treatment, further, no change was found in the glass compositions. When the atmosphere for the heat treatment is altered as described above, the reversible coloring and decoloring can be performed.

Example

Example 3

A glass having a composition containing, by mol %, 23.9% of P2O5, 19.8% of WO3, 14.8% of Nb2O5, 4.9% of TiO2, 15.2% of Li2O, 5.8% of Na2O, 2.5% of K2O, 11.1% of BaO and 2.5% of B2O3 was prepared by melting at 1,100° C. The obtained glass had a blackish blue color. The glass was formed into a sheet having a thickness of 2 mm by cold working, and the glass having a sheet form was heat-treated under atmosphere of air at 515° C. As the time period of the heat treatment increased, the blackish blue color of the glass came to be lighter. FIG. 3 shows a change of a transmittance spectrum in the heat treatment under atmosphere of air. As shown in FIG. 3, the minimum transmittance was controlled to be in the range of from 64% to 80% by carrying out the heat treatment for a period of time up to 6 hours.

There was found no change that was caused on the glass composition by the above heat treatment.

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Abstract

Provided are a process for the production of a precision press-molded article having a high transmittance and a method of treating a glass to color or decolor the glass, the process comprising heat-treating a press-molded article containing at least one selected from WO3, Nb2O5 or TiO2 in an oxidizing atmosphere to produce a glass molded article, and the method comprising heat-treating a colored glass containing at least one oxide of WO3 and Nb2O5 in an oxidizing atmosphere to decolor the glass, or heat-treating a glass containing at least one oxide selected from WO3, Nb2O5 or TiO2 in a non-oxidizing atmosphere to color the glass.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of the Invention The present invention relates to a process for the production of a glass molded article, an optical element produced by the process, and a method of treating a glass. More specifically, it relates to a process for efficiently producing a transparent glass molded article by decoloring a press-molded product, an optical element produced by the above production process and a method of treating a glass, particularly, an optical glass, for coloring and decoloring the glass. 2. Prior Art of the Invention In recent years, as a technique for mass-producing glass optical elements such as aspherical lenses, increasing interests are invited to a precision press-molding technique of press-molding a glass material made of an optical glass with a mold having a transfer molding surface having a reversal form of an optical element as an end product thereby to obtain a high-precision optical element without cutting and polishing aft...

Claims

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Application Information

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IPC IPC(8): C03B11/00C03B11/08C03B32/00C03C1/10C03C3/16C03C3/21C03C4/02
CPCC03B11/005C03B11/08C03B32/00C03C4/02C03C1/10C03C3/16C03C3/21C03B2215/66
Inventor HAYASHI, KAZUTAKATAWARAYAMA, HIROMASAZOU, XUELUKAWAZOE, HIROSHI
Owner HOYA CORP
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