Silicone Fluids & Silicone Emulsions

Benefits and application areas of silicone fluids

Silicone fluids possess

• Extremely low volatility
• Excellent shear stability
• Low surface tension, and
• Optimum water repellency.

Silicone fluids have no known harmful effects and are transparent liquids that have no taste or odor. Their viscosities lie between 0.65 and 1,000,000 mm²/s, depending on the type. Since there are only very weak intermolecular forces between the individual methylsilicone chains, they are liquid over wide ranges of their molecular weight.

Thanks to these properties, silicone fluids make ideal

• Hydraulic and transformer fluids,
• Damping fluids,
• Diffusion pump fluids,
• Heat-resistant lubricants,
• Dielectrics,
• Defoamers, and
• Release agents for high-performance digital-printing machines.

They are also used for water-repellent treatment of glass and mineral wool and for various applications in cosmetics, pharmaceuticals and textiles.

Functionalization of silicone fluids

The siloxane backbone is most often modified in two ways:

1. Instead of methyl groups, longer alkyl chains are attached
2. Functionalization is performed with organic polymers . For example, polyethylene oxide, polypropylene oxide or alkylamino groups can be used for this.

This affords a way of transforming hydrophobic silicone fluids into more or less hydrophilic molecules.

Reactive silicone fluids are siloxanes terminated with reactive groups. They include, e.g. OH polymers (hydrolyzates) or silicone fluids with amino or epoxy groups.

Macroemulsions and microemulsions

There are basically two types:

1. Macroemulsions with particle sizes from 100 nm to several μm, usually opaque, i.e. milky.
2. Microemulsions with particle sizes less than 100 nm. These are usually clear or opalescent.

To provide a stable silicone emulsion, the surfaces of the fluid droplets are covered with surfactants (emulsifiers). The lipophilic or oil-loving ends of the emulsifier are oriented toward the oil droplet. The hydrophilic – water-loving – centers provide solubility in water.

Silicone emulsions are typically used in the textiles, cosmetics and household care industries. As components of shampoos, silicone emulsions lend hair a silky softness, making it easy to comb after washing. Silicone emulsions are also used as water-repellent agents for protecting textiles or building and insulation materials against water and damp.

Lubricating and assembly pastes

Silicone pastes have certain basic properties that enable them to be used in various applications:

• They do not harden and their properties are virtually unaffected by changes in temperature.
• They are water-resistant, water-repellent and oxidation-resistant. They are thus extremely durable and form protective layers against the elements and on a wide range of surfaces.
• They are odorless, of a low order of toxicity, radiation-resistant up to approx. 106 rad, inert with respect to a great many chemicals, and resistant to microorganisms.
• They have ready adhesion to numerous surfaces and good lubricating properties in plastic/plastic or plastic/metal pairings. They also have good lubricity.
• They have good release action with respect to numerous elastomers and plastics.
• They guarantee good electrical insulation. They also have a high breakdown strength, high dielectric constant and low loss factor.
• They are very stable in storage. Functionality of specific properties lasts for up to 12 months while general properties will last for several years.

Silicone pastes are used, for example, as lubricants and installation aids, both for technical purposes and in food-contact applications, and as sealing aids for sealing parts and connections that can be disassembled, and as release agents for high-temperature use.

Water-repellency and structure

Silicone waxes are polydimethylsiloxanes that are modified by long-chain alkyl groups. To an extent depending on the chain length and number of alkyl groups, modification yields products of different melting point. They behave like typical hydrocarbon waxes.

Silicone waxes combine the properties of organic waxes – such as water repellency or providing structure – with the typical properties of silicones, such as wetting power and good sensory properties.

They are thus ideally suited to all applications in which lubrication is required and the transition from solid to liquid is critical. Silicone waxes are used as oil and wax components in skin and face creams, or in decorative cosmetic articles for improving the skin feel. In addition, silicone waxes optimize the distribution of pigments and sunscreen additives and increase the spread of oils and active compositions. In the textile sector, for example, leather is treated with silicone waxes. These confer very good long-term protection and have a water-repellent effect.

The Right Product for Every Application

Silicone antifoam compounds are oily, viscous, opaque or slightly cloudy liquids. They are mostly used in systems containing little or no water. The compounds can be used neat or mixed with suitable formulation components such as surfactants.

Self-dispersing silicone antifoam agents are a combination of antifoam agent compounds with organic active agents and auxiliaries. They disperse spontaneously on contact with foaming formulations and show good compatibility and spreading properties.

Silicone antifoam emulsions are o/w emulsions of antifoam agent compounds with an active content of 5 to 50%. They are mainly used for water-borne formulations and applications.

Silicone antifoam powders are ideal for use in powder products, such as powder-form detergents.

Silicone fluids are characterized by good antifoam properties in water-free, non-polar systems. They are suitable for applications in which compatibility with other substances is not required.