As currently used in sealant compounding, commercial tetra-functional Tetra(methylisobutylketoxime)silanes are either mixed (dissolved) in trifunctional oximino silanes or dissolved in organic solvents.
In the former case solubility limits the level of tetrafunctional oximino silane in the trifunctional oximino silane to 35-40% at room temperature. This is disadvantageous because higher levels of tetrafunctional oximino silane increase cure rate and minimize (if not eliminate) the need for a catalyst.
In the latter case, solid tetrafunctional oximino silanes were mixed with hydrocarbons like toluene, benzene and xylene, organic ethers like diethylether and dibutylether, ketones and halogenated solvents to facilitate ease of handling in applications which require precise amounts of tetrafunctional oximino silane. Because some of these solvents are flammable and carcinogenic, further precautions must be taken to ensure the safety of personnel during processing. In addition, one must ensure that the vapor emissions from the finished sealant products generated during end use are safe for people and the environment. These precautions are both costly and time consuming.
Solubility is also a concern. That is, for example, at room temperature, tetrafunctional MEKO-based silane is only 50% soluble in toluene and in methyl ethyl ketoxime, 40% soluble in diethyl ether and 10% soluble in dibutyl ether. As a result, significant amounts of solvent may be required in the formulation. In addition, crystallization can occur at lower temperatures (i.e., e.g., during shipping in winter months) and at higher concentrations of the tetrafunctional oximino silane.
Because of this, there has been a long felt need in the industry for tetrafunctional oximino silanes which do not require organic solvents or mixing with trifunctional oximino silanes. We have surprisingly discovered that the novel tetrakis oximino silane, e.g. tetrakis-(methyl isobutyl ketoximino) silane is liquid and thus do not suffer with the same problems as their solid counterparts. These new silanes offer the ability to employ solvent-free formulations, if not significantly decrease solvent content in the composition. In addition, there is added flexibility and simplification when formulating room temperature moisture-curable silicone compositions. Because the new silanes are liquid tetrafunctional oximino silanes, one can add more of these silanes to increase the cure rate of the composition. The amount of other tetrafunctional oximino silanes which can be used in this type of silicone composition is limited by their solubility in the solvent.
In addition to the novel liquid tetrafunctional oximino silanes, we have also found that when these novel oximino silanes (tetra-oximino, tris-oximino or bis-oximino) are formulated with hydroxyl terminated polydimethylsiloxane (HTPDMS), an optically clear silicone rubber results.
Technical Properties
Empirical Formula
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C24H48N4O4Si
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Molecular Weight
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484.75
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Boiling Point
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N/A°C
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Flash Point
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N/A°C
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Color and Appearance
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Colorless or yellowish transparent liquid
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Density [25°C]
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N/A
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Refractive Index [25°C]
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N/A
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Purity
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90.0% by GC
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Applications
The Tetra(methylisobutylketoxime)silane is used as a novel neutal curing agent in silicone sealant formulations.
Obiteljski obrt. Fotografiranje, video snimanje, pozivnice i zahvalnice. International engineering firm serving primarily the energy and process industries. Located in Connecticut. Animal feed and accessories for aquarium and garden pond, with tips and question forum. [D-49324 Melle]
Obiteljski obrt. Fotografiranje, video snimanje, pozivnice i zahvalnice. International engineering firm serving primarily the energy and process industries. Located in Connecticut. Animal feed and accessories for aquarium and garden pond, with tips and question forum. [D-49324 Melle]
Fine-chemical producer in China specializing in brominated organics and silane derivatives, also offering several miscellaneous products. Provides information on oxygenated and hydrocarbon solvents. Topics include applications, properties, and regulatory details, with links to publications and members' sites. Solvon is a manufacturer of nPropyl Bromide (nPB) Solvent
Discussion group for the work of Georges Dumézil on Indo-European mythology and trifunctionality. Manufactures specialty silanes and silicones including inert silicones for engineering applications and reactive silicones for formulation. PC Silicone supplies silane fluids, coupling and crosslinking agents, from China.
