Crystallization-free glass frit compositions and frits made therefrom for microreactor devices

Abstract

The invention is directed to a glass composition that can be used to make glass frits suitable for use in the manufacturing of microreactors. The glass compositions, after final sintering to produce a finished microreactor, have a surface crystalline layer of 30 μm or less, or are completely amorphous throughout. Generally, the borosilicate glasses of the invention have a composition of B₂O₃=12-22 mol %; SiO₂=68-80 mol % and additional components selected from the group consisting of either (a) Al₂O₃=3-8 mol % and Li₂O=1-8 mol %, or (b) K₂O=0-2 mol % and Na₂O=0-2 mol %, except that both K₂O and Na₂O cannot both equal zero at the same time. One borosilicate glass has a composition, in mole percent (mol %) of B₂O₃=18-22 mol %, SiO₂=75-80 mol %, K₂O=0-2 mol %, and Na₂O=0-2 mol %, except that both K₂O and Na₂O cannot both equal zero at the same time.

Description

CLAIM OF PRIORITY [0001] This application claims the benefit of priority under 35 U.S.C. § 119 of European Patent Application Serial No. 05292534.4 filed on Nov. 30, 2005. FIELD OF THE INVENTION [0002] The invention is directed to crystallization-free glass frits that are suitable for the manufacturing of glass microreactor using micro-molding technology and to the glass compositions used to make such frits; and in particular to glass frits that exhibit resistance to thermal shock and have excellent chemical durability. BACKGROUND OF THE INVENTION [0003] As a result of economic forces, environmental considerations, waste disposal regulations and other factors, activities in the fields of thermal and chemical process engineering have gravitated toward the use of microreactors for research and development, including modeling studies and chemical reactions. In addition, microreactors are finding application in pharmaceutical and biological research, development and analysis. A microrea...

AI Technical Summary

Benefits of technology

[0006] The invention is directed to glass compositions having a low softening point low CTE, high acid and alkali chemical resistance, and high crystallization resistance that are suitable for manufacturing glass frits for microreactors. The glasses of the invention are borosilicate glasses containing either (a) lithium oxide plus aluminum oxide or (b) sodium oxide or potassium oxide. The glasses of the invention have a crystallized depth layer, as measured by the HTS method described herein using bulk glass, of less than 30 μm, preferably less than 20 μm, and most preferable 10 μm or less. The substrates used in practicing the invention can have a CTE in the range of 25-40×10−7 / ° C., preferably in the range of 30 to 40×10−7 / ° C.

Problems solved by technology

While the simple design illustrated in FIG. 1 is satisfactory for some reactions, for others a more complex design is required.

As a result the design of the reactor can become quite complicated; which in turn means that the construction of the reactor itself becomes complicated and expensive if etching techniques are used to construct parts of the microreactor.

In addition, while materials such as metals, silicon and certain polymers can be used to fabricate microreactors, these materials are not well suited for chemical reactions at high temperature and / or that use corrosive reactants.

As mentioned in U.S. 2004 / 0152580 A1, the problem with PYREX® glass frits is that they undergo devitrification (that is, crystals of different materials are formed) during sintering at temperatures in the range of 700-800° C. However, there is a lowering of mechanical strength due to both the formation of crystals with a high coefficient of thermal expansion and the volume change that is associated with the phase transformation of cristobalite crystals at approximately 200° C. This can lead to frit cracking on cooling after sintering.

The addition of alumina causes the sintering ability of the frit to decrease and reduces the fluidity of the frit.

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