Clear glass composition with high visible transmittance

#This invention relates to glass compositions and methods of making the same. More particularly, this invention relates to glass having high light transmittance in the visible range and/or fairly neutral color. Such glass compositions are useful, for example, in architectural windows, patterned glass applications, residential windows, furniture, solar cells, and/or automotive windows.

#Glass that is fairly neutral or clear in color, and highly transmissive to visible light (e.g., at least 75% transmissive, or even more preferably at least 80% transmissive), is sometimes desirable. One way of achieving such a glass is to use very pure base glass materials (e.g., substantially free of colorants such as iron). However, base materials with a high degree of purity are expensive and thus not always desirable and/or convenient. In other words, for example, the removal of iron from glass raw materials has certain practical and/or economical limits.

#As can be appreciated from the above, glass raw materials (e.g., silica, soda ash, dolomite, and/or limestone) typically include certain impurities such as iron. The total amount of iron present is expressed herein in terms of Fe2O3 in accordance with standard practice. However, typically, not all iron is in the from of Fe2O3. Instead, iron is usually present in both the ferrous state (Fe2+; expressed herein as FeO, even though all ferrous state iron in the glass may not be in the form of FeO) and the ferric state (Fe3+). Iron in the ferrous state (Fe2+; FeO) is a blue-green colorant, while iron in the ferric state (Fe3+) is a yellow-green colorant. The blue-green colorant of ferrous iron (Fe2+; FeO) is of particular concern when seeking to achieve a fairly clear or neutral colored glass, since as a strong colorant it introduces significant color into the glass. Ferrous iron is typically a stronger colorant than ferric iron. Thus, while iron in the ferric state (Fe3+) is also a colorant, it is of less concern when seeking to achieve a glass fairly clear in color.

#Glass according to certain example embodiments of this invention is capable of achieving high visible transmission while at the same time realizing fairly neutral or clear color. Glasses according to different embodiments of this invention may be used in the context(s) of architectural windows, patterned glass applications, residential windows, furniture, solar cells, and/or automotive windows.

#Certain glasses according to this invention utilize soda-lime-silica flat glass as their base composition/glass. In addition to base composition/glass, a unique colorant portion is provided in order to achieve a glass that is fairly clear in color and/or has a high visible transmission. An example soda-lime-silica base glass according to certain embodiments of this invention, on a weight percentage basis, includes the following basic ingredients:

#TABLE 1 EXAMPLE BASE GLASS Ingredient Wt. % SiO2 67-75% Na2O 10-20% CaO 5-15% MgO 0-8% Al2O3 0-5% K2O 0-5%