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Organosilanes and Voltique 75’s Improvements

There is a huge difference between water-stable QAC's and companies simply putting a methanol-based QAC into the water - these products cannot bond to surfaces, last in the container or remain active like Voltique, plus the makeup of these products creates a far more toxic substance which needs to be handled far more sensitively.

The DOW Corning 5700 is a commercially relevant example of an organosilane suffering from undesirable self-condensation in water. Moreover, in the presence of water the propyl trimethoxysilane portion of the molecule converts into a propyl trihydroxysilyl moiety and polymerizes through Si--O bonds to hydroxylated surfaces of the substrate and through intermolecular O--Si bonds.

The C.sub.18 hydrocarbon chain quaternary ammonium portion of the molecule possesses long-acting antimicrobial properties and provides initial association with the surface of the substrate through ionic bonds and/or electrostatic interaction, chloride is to add a dilute solution of 3-(trimethoxysilyl)propyl-dimethyloctadecyl ammonium chloride in methanol to water. This addition rapidly converts the --Si(OCH.sub.3).sub.3 portion of the molecule into a reactive --Si(OH).sub.3 group thereby activating -dimethyloctadecyl ammonium chloride and water, which are generally unstable and prone to self-condensation. For instance, the mixture of 3-(trimethoxysilyl)propyl-dimethyloctadecyl ammonium chloride and water begins to lose effectiveness of the molecule. The activated 3-(tri methoxysilyl/trihydroxysilyl)propyl-dimethyloctadecyl ammonium chloride system must then be used within a short period of time, such as a few hours to at most about 12 hours, to treat a surface or fabric to produce a permanent surface coating.

Unfortunately, as noted above, organosilanes in water, such as the activated mixture of 3-(trihydroxysilyl)propyl in as little as four to eight hours, a gel formation in this and similar silane formulations in the water begins to occur in even shorter times. Moreover, such products are notorious for agitation difficulty during the addition of the silane to water.

While these quaternary ammonium silicon compounds have been employed to sanitize, sterilize or disinfect many surfaces, their employment is still limited because of their toxicity often as a result of the solvent system used to deliver the compound, the necessity for a solvent solution (for instance, Dow Corning antimicrobial agents contain 50% methanol), short term stability (stability of aqueous silane solutions varies from hours to several weeks only) and poor water solubility. For instance, while 3-(trimethoxysilyl)propyl-dimethyloctadecyl ammonium chloride does not suffer from water insolubility, it is unstable in water and also, because it is shipped in 50% methanol, it is overly toxic. Many other antimicrobial organosilanes using similar solvents, especially quaternary ammonium silicon compounds, also suffer from problems associated with physical health hazards, e.g., precautions must be taken to avoid contact with both skin and eyes, accidental spills to the surrounding area, flammability, and the added manufacturing steps needed in order to incorporate the antimicrobial agents into other articles and surfaces, resulting in much higher manufacturing cost.

Therefore, there existed a need for extended shelf-life, water-stable organosilane compounds, products and compositions whereby, upon application, the active portion of the organosilane is operative for the selected application. Moreover, there existed a need for water-stable, organosilane compounds, products and compositions which are essentially non-toxic, non-flammable, uniformly dispersible, and simple and economical to use.

To accomplish the water stable objective a polyol containing at least three hydroxy groups, wherein all of the hydroxy groups are separated by at least three intervening atoms, must be employed in the manufacturing of the organosilane formula or the self-condensation of the formula will occur. This stabilizing compound is used in the Voltique 75 organosilanes.

It should be further noted that many substrate compositions have been developed and or adopted since the original DOW formulas were developed. Many of these are inert materials with no sites for attachment [no bonding capabilities] and other substrates that have various degrees of interfacial surface tension that should be broken down so the non-polar covalent bonding can occur, which can/will impact better substrate coverage. Again, this is attributed to nonionic inert compounds in the Voltique 75 formulations.  Therefore, I would suggest that the classification of organosilanes differ greatly in composition and most importantly in the ultimate performance and thus should be distinguished from one another, and preferably not grouped or identified as being very similar under the same banner of trimethoxysilyl quaternary ammonium compounds, but more simply as the “silane quat(s) ”, however, on Voltique 75 it should be noted with the distinguishing features of being water stable, and surface penetrating which will result in better efficacy. 

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