Transparent infrared absorbing glass and method of making

a technology of infrared absorption and transparent glass, which is applied in the field of production of glass, can solve the problems of disadvantageous economic electric melting of large-scale flat glass manufacturing, undue compromising of the overall transmittance properties of glass, and achieves low infrared transmittance, high luminous transmittance, and low total iron content

Inactive Publication Date: 2001-08-14
PPG IND OHIO INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention relates to a glass composition that has low infrared transmittance and high luminous transmittance. This is achieved by minimizing total iron content, reducing glass above 50 percent ferrous, and very low sulfur content. The lower sulfur levels are achieved by avoiding sulfur-containing refining aids and using vacuum to remove sulfur from the melt. The use of melting and refining processes based on discrete stages with minimal volumes of molten material being retained is preferred. The iron colorant can be added at different stages in the process to expedit color changes. The glass also has reduced ultraviolet transmittance, which can be achieved by adding cerium oxide to the glass.

Problems solved by technology

The technical problem addressed in this patent text is to create a glass composition with low infrared transmittance (measured at 5 mm) that also has low ultraviolet transmittance, without compromising the ability to melt and refine the glass. The conventional methods for reducing infrared transmittance often resulted in high levels of sulfur dioxide in the glass, which negatively impacted its coloration and made it difficult to achieve desired levels of luminous and thermal transmittance. The present invention aims to provide a glass composition with low infrared transmittance and low ultraviolet transmittance levels.

Method used

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  • Transparent infrared absorbing glass and method of making
  • Transparent infrared absorbing glass and method of making
  • Transparent infrared absorbing glass and method of making

Examples

Experimental program
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Effect test

example i

In a glass melting and refining operation essentially as shown in FIGS. 1 and 2, color additive was stirred into the refined glass at a rate of about 0.85% to 1.0% by weight of the glass. The additive was a color concentrate identified as KG-947-B by its manufacturer, Ferro Corporation, Orrville, Ohio, and contained about 40% iron in the form of magnetite (Fe.sub.3 O.sub.4). The glass had 0.118% total iron before the addition and 0.479% to 0.495% total iron after the addition. The ratio of FeO to total iron after addition ranged from 0.47 to 0.55, and SO.sub.3 content was 0.003% to 0.005%. The resulting glass in a 5 millimeter thickness exhibited LT.sub.A of 68.4% to 69.3% and infrared transmittance of 11.2% to 13.9%.

example ii

In a glass melting and refining operation essentially as shown in FIGS. 1 and 2, an iron-containing additive was included in the batch mixture in the amount of 1.9% by weight of the batch. The additive was "Melite 40" a nearly sulfur-free CaO--Al.sub.2 O.sub.3 --SiO.sub.2 slag containing about 20% by weight total iron, with about 80% of the iron in the form of FeO sold by the Calumite Company, Boca Raton, Fla. The batch mixture also included 0.025% by weight powdered coal to enhance reducing conditions during melting. Combustion burners in the liquefying stage were operated with reducing flames at a volume ratio of 1.9 parts oxygen to one part methane. The resulting glass had a total iron content of 0.449% to 0.473%, with a ratio of FeO to total iron of 55.6% to 60.6%. At a thickness of five millimeters, the glass exhibited LT.sub.A of 68.6% to 69.9% and infrared transmittance of 10.9% to 12.9%.

The above two examples disclose two additives that serve as iron sources with a relativel...

example iii

In a glass melting and refining operation as shown in FIGS. 1 and 2, color concentrates were melted in a small furnace and fed in molten form into the stirring chamber at about 2400.degree. F. (1315.degree. C.). The concentrates were KG-947-I containing about 40% by weight total iron, about 60% of that iron being in the form of FeO, and MI-380-B containing about 25% by weight CeO.sub.2, both sold by the Ferro Corporation. The iron color concentrates was added at the rate of 12 parts by weight per thousand parts by weight of base glass, and the cerium color concentrate was added at the rate of 20 parts to one thousand parts by weight. The total iron content of the glass increased from 0.082% by weight Fe.sub.2 O.sub.3 to 0.533% Fe.sub.2 O.sub.3 in the final glass composition with a ratio of FeO to total iron of 0.522. The final glass composition had 0.44% by weight CeO.sub.2 and less than 0.001% by weight SO.sub.3. The transmittance properties of a five millimeter thick sample of the...

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Abstract

A glass product having high visible transmittance, low infrared transmittance, and, optionally, reduced ultraviolet transmittance is produced in a manner compatible with continuous, commercial manufacture of flat glass by employing a moderate amount of iron in the glass composition and controlling reducing conditions to maintain a relatively large portion of the iron in the ferrous state.

Description

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Claims

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Application Information

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Owner PPG IND OHIO INC
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