XIAMETER® brand silicone emulsions are based on different-viscosity silicone polymers. The higher the viscosity of the silicone fluid used in the emulsion, the more substantive the resulting emulsion will be.
Medium-viscosity silicone fluids yield emulsions that deliver good wet-out and gloss with a minimum of smear.
High-viscosity silicone fluids yield emulsions that deliver excellent gloss, conditioning and shine, and more efficient release.
Ultra-high-viscosity silicone gums yield emulsions that deliver superior gloss.
Surfactants In XIAMETER® Brand Silicone Emulsions
XIAMETER® brand silicone emulsions may be formulated with nonionic, anionic, or cationic surfactants. The type of emulsifier used defines the emulsion’s ionic character.
Nonionic – Emulsion particles show no net charge and can be used in a variety of systems (nonionic, anionic, cationic, or polymer) without forming a complex.
Anionic – Emulsion particles have a net negative charge, typical of formulations based on the saponification of a fatty acid, such as oleic acid, and an alkali.
Cationic – Emulsion particles have a net positive charger similar to alkyl quaternary compounds, giving good wetting and substantivity properties as well as synergy with silicones.
Emulsion choice is based on the compatibility of the surfactant with the application formula and the mechanism of silicone action or deposition.
How Surfactants Work
The surfactant migrates between the two phases (silicone and water) and remains at the interface, where it stabilizes the repulsion forces of the two phases.
A silicone must generally deposit itself on a substrate to provide its benefits. This is triggered either by the polymer functionality and/or by the emulsion surfactant system used in synergy with the application formulation.
Originally published in 2007 as part of a chapter on “Silicones in industrial Applications” in Inorganic Polymers (an advanced research book by Nova Science Publishers).
Practical information about the uses, benefits and limitations of silicones in industrial applications.
Microbial contamination – emulsions
Silicone emulsions can be contaminated by:
- Food – any nitrogen or carbon source
- Temperature – between 10 and 50˚C (50 and 122˚F)
These conditions are present in many industrial environments. Consequently, it is best to use a diluted emulsion as soon as possible.
Applying release agents to new molds
Break in a new mold by applying a coat of silicone release agent emulsion as supplied and running one or two empty heat cycles.
Dilution levels for release agents
Dilution ratios vary considerably. Refer to the product technical data sheet for the specific product you’re using.
Typically, it is suggested to dilute to 2 to 5% silicone solids as a starting point.
Experiment in small scale to find the adequate dilution that will achieve the ease of release and number of releases desired.
Release agents for high-temperature applications
Emulsions of higher-molecular-weight polydimethylsiloxanes are preferred for high-temperature release applications. Emulsions made from alkylaryl siloxane copolymers (available from Dow Corning under the Dow Corning® brand name) also show excellent thermal stability.
Rust inhibitors for diluted release agent emulsions
Polydimethylsiloxane emulsions used in industrial release and printing web release applications often contain sodium benzoate as a rust inhibitor to help prevent corrosion on metals (e.g. steel, zinc, copper, copper alloys, aluminum and aluminum alloys).
Sodium benzoate can be added to a level of 0.1% weight in the diluted emulsion. A suitable pH range for effective inhibition is about 6 to 12.
Applying aminosilicone softeners to fabric
Silicone softeners are generally applied to fabric by padding or exhaustion.
Padding involves physically penetrating the textile substrate with the aminosilicone emulsion using rollers connected to the emulsion bath. The amount of silicone applied to the fabric is determined by the water pickup of the fabric and the concentration of the emulsion. The more water the fabric absorbs, the less concentrated the emulsion has to be.
Exhaustion is a “nonforced” application. It is mainly driven by the affinity of the aminofunctional polymer to the respective fibers. The extent to which the aminosilicone will deposit onto the fibers will vary depending on the type of fiber. But in general, for natural fibers like cotton, which have a slight negative charge at the surface, cationic emulsified aminosilicones show good exhaustibility.