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Silane Crosslinkers | Oximino Silanes | Oxime Silane | MIBKO Silane | Neutral crosslinkers

SiSiB® PC7530

Synonym: Vinyl tris (MIBKO) silane.
Vinyl tris-(methyl isobutyl ketoximino) silane
Chemical Structure


The problem with known tetrafunctional oximino silanes (i.e., e.g., those based on methyl ethyl ketoxime (MEKO) and acetone oxime) is that they are solids at room temperature. Since such compounds are very sensitive to moisture they decompose easily to semisolids which are difficult to handle. Thus, these materials have a poor shelf life and require special care in their packaging and transporting.

The known tetrafunctional and trifunctional oximino silanes (i.e., e.g., those based on MEKO and acetone oxime) have other drawbacks. Traditionally, when these materials have been combined with silicone polymers the resulting product has been opaque. This has substantially limited the applications in which these materials can be used.

As the applications in which room temperature curing compositions can be utilized continue to increase, the specific kinds of properties required of these compositions continue to change.

So we are continually looking for room temperature curing compositions having new desirable properties without the old undesirable properties like opacity and physical state limitations (solids). We have surprisingly discovered these silanes satisfy this need.

Methyl tris-(methyl isobutyl ketoximino) silane
Vinyl tris-(methyl isobutyl ketoximino) silane
Tetrakis-(methyl isobutyl ketoximino) silane

As currently used in sealant compounding, commercial tetra-functional oximino 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. [From US5,717,052]
Typical Physical Properties
Chemical Name: Vinyltris(methylisobutylketoxime)silane
CAS No.: 156145-64-1
EINECS No.: 421-860-7 (ELINCS)
Empirical Formula: C20H39N3O3Si
Molecular Weight: 397.63
Boiling Point: 290°C
Flash Point: 62°C
Appearance: Clear to straw clear liquid
Assay: Min. 90.0%
Total Low Boilers Max. 6.0%
Total High Boilers Max. 5.0%
MIBKO content Max. 3.0%
SiSiB® PC7530 is used as a novel neutal curing agent in silicone sealant formulations.

GUIDE - SiSiB SILANES & SILICONES - RTV-1 formulation solution
Net weight 180Kg steel drum or 900Kg IBC container, for more details, please visit Packing Centre.
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