Coatings

This expression covers a myriad of applications mainly as a thin surface deposit of polymer onto a base substrate, which can include;

• Conformal coating on a printed circuit board
• Textile coating on industrial conveyors and bellows or apparel
• Hardcoats on plastics for scratch resistance on headlights
• Weatherstrip coating for friction reduction of rubber products

The key to success in all of these is securing adhesion to the base material otherwise performance will be inconsistent, at best.

Our expertise covers all 4 areas but commercially we only support conformal and textile coating.

Silicone Coatings

Silicones are a remarkably versatile family of synthetic materials with hundreds of uses. Chemically they are related to SiO2 like quartz or sand but contain organic
residues, which break down the inflexible threedimensional network. The inorganic Si-O-Si backbone is the reason for the unique silicone properties. Methyl is the preferred substituent because of the weak interaction between the methyl groups and low proportion of organic material in the polymer.

Key benefits of silicone elastomers are:

• High temperature resistance and low temperature flexibility
• Stability against ageing by UV, ozone and harsh weather conditions
• Physiological inertness and applicability in food applications and skin contact
• High hydrophobicity and low surface energy
• Neutral odor, taste and color
• Solvent free
• Soft touch

Momentive Silicone Elastomers Product lines are:

RTV – Room Temperature Vulcanizing:

Consists of rubber and gel products developed for adhesion, sealing, coating, and encapsulation/potting applications. Momentive’s versatile technology offers 1 and 2 component products, which utilize either atmospheric moisture or heat to cure. Chemically they are condensation cure or addition cure products.

LSR – Liquid Silicone Rubber:

This addition cure material is mainly designed for short cycle time injection molding and fully automatic processing. Coating grades are usually at the low end of the
viscosity range. General Purpose LSR products can also be used for coating applications in diluted form

HCR – High Consistency Rubber:

Typical processes include extrusion, calandering, molding (incl. compression, transfer and injection). Momentive Performance Materials supplies base materials for
customers with their own compounding. We are also capable to supply ready-to-use-compounds including the peroxide cure or addition cure catalyst in 1 or 2 components. HCR products are diluted in solvents for coating applications.

Silicone Materials for Textile Coating

Today addition cure is the preferred technology for coating of textiles with silicones. Solvents can usually be avoided and no by-products are generated during cure. The addition reaction is very fast and work life can be adjusted to the needs of the application. The curing conditions can vary between less than a minute at ambient temperature with 20 seconds pot life and several minutes at 150°C with a pot life of days. Even 1- part addition cure materials are possible.

• Both products RTV and LSR are based on the addition reaction. The designation as LSR or RTV is not always logical in textile coating because both product types are cured at elevated temperature. The naming is based on the product and application history.
• The Silicone Liquid Elastomers (SLE) products are resin type textile coatings. They are a very good choice when a smooth and non-blocking surface is required.
• HCR and RTV 1-part condensation cure products for coating are not included in this brochure. Information is available upon request.

Elastomer Textile Coating Overview