Wacker Elastosil® RT 629 A/B – Antistatic Addition Curing Silicone for Pad Printing & Printing Pads

Premium Antistatic Addition Silicone for Professional Pad Printing and Industrial Printing Applications

ELASTOSIL® RT 629 A/B is a pourable, addition-curing (platinum-cure) two-component silicone rubber that vulcanizes at room temperature (RTV-2). The cured rubber is turquoise, has an average hardness of Shore A 31 and a low mixing viscosity of 8,000 mPa·s, giving the material excellent flow properties and good self-deaeration. Its unique feature is its antistatic equipment, which quickly dissipates static charge on the surface of the printing pad. With a processing time of approximately 40 minutes, a tack-free curing time of 3 hours at room temperature, and a mixing ratio of 10:1 by weight, this is a fast and shrinkage-free system for the professional production of antistatic pads.

Key Benefits

• Hardness Shore A 31 – average hardness that provides the right balance between dimensional stability and ink transfer for printing pads.
• Tear strength 25 N/mm – high mechanical strength and long-term hardness consistency for a long pad service life.
• Tensile strength 6 N/mm² and elongation at break 500% – excellent elasticity that withstands repeated impressions without fatigue.
• Mixing viscosity 8,000 mPa·s – very good flowability and self-deaeration for bubble-free, detailed casts.
• Processing time 40 minutes – ample pot life with fast, shrinkage-free curing in 3 hours, which can be further accelerated with heat.
• Antistatic properties – rapid dissipation of static charge, essential when printing sensitive electronic components.

Typical Applications

• Production of antistatic printing pads for industrial pad printing.
• Printing of keyboards, switches, and control panels.
• Printing of sensitive electronic components where static discharge must be avoided.
• Printing of toys, sporting goods, and automotive parts.
• High-volume printing applications with high printing speed and high printing accuracy.
• Hardness adjustment with Wacker Silicone Fluid AK 35 for softer pads.

Processing Instructions

1. Stir component A and component B thoroughly and separately in their containers to evenly distribute any settled fillers.
2. Weigh in a 10:1 ratio (A:B) by weight. Important: only use A and B components with the same batch number. The platinum catalyst is in component B.
3. Mix A and B slowly and thoroughly (figure-8 or mechanically), scraping the sides and bottom until a homogeneous, streak-free mixture is achieved.
4. Optional: deaerate the mixture under reduced pressure (10–20 mbar) in a vacuum chamber.
5. Pour within the pot life of approximately 40 minutes in a thin stream from a low height.
6. Allow to cure for approximately 3 hours at room temperature. Curing can be significantly accelerated by heating.

Inhibition with Addition Curing

ELASTOSIL® RT 629 A/B is an addition-curing (platinum) silicone and is therefore sensitive to inhibition. Substances such as sulfur and sulfur-containing compounds, amines, tin compounds, condensation silicones, and certain modeling clays can slow down or prevent curing. If in doubt, always perform a preliminary test and keep incompatible materials away from the fresh mixture.

Processing and Dilution

The hardness can be reduced by adding Wacker Silicone Fluid AK 35. The dilution table shows the Shore A and Shore 00 hardness at different oil percentages.

About the Manufacturer

Wacker Chemie AG is a world leader in the development and production of silicones for industrial and technical applications.

Professional Support

Do you need advice on the correct hardness, dilution, or processing for your pad printing application? Feel free to contact us – our specialists will be happy to help you choose and process the right material.