WACKER® PRIMER G 719
solvent-based mixture of siloxanes and reactive silanes used as adhesion promoter for silicone rubbers
- Provides excellent adhesion onto various substrates.
- Solvent based
- Various application methods (e.g. coating, dipping, brushing, spraying)
- Further dilution in organic solvents possible
WACKER® PRIMER G 719 is a solution of a siloxanes and reactive silanes in organic solvents. It is used to pretreat metallic, ceramic, glass or other polymeric substrate surfaces to enable excellent adhesion towards subsequently vulcanized ELASTOSIL® R plus or LR silicone elastomers (addition curing).
After the solvents have evaporated, a rigid film of silicone resin is formed on exposure to atmospheric humidity. The primer film adheres firmly to a large variety of substrates and serves as adhesion promoter for subsequently applied silicone rubbers.
It is recommended to clean all substrate surfaces with solvents (e.g. white spirits followed by ethanol or acetone) prior to the application of WACKER® PRIMER G 719. The primer may be applied directly or in diluted form with a variety of application methods (e.g. coating, dipping, brushing or spraying). It is recommended to stir the primer thoroughly before application.
The resulting primer layer should be as thin as possible. Usually the best results can be achieved with a primer layer between 1 an 10 µm thickness. If the primer needs to be diluted, organic solvents like white spirits or ISOPAR® E can be used in a ratio of 1:1 - 1:10.
After application of the primer, the solvent should be evaporated at room temperature and moderate atmospheric humidity for at least 30 minutes to allow for the formation of a consistent primer film. It is recommended to apply the silicone rubber soon afterwards, but not later than 2 days. In some cases the adhesion can be improved by heating the primered substrate after evaporation of the solvents to 100°C for up to one hour.
It is important to note that in some cases the initial adhesion will be sufficient for handling while the maximum adhesive strength will be achieved after a few days.
When adhesion of silicone elastomers onto very smooth substrates has to be achieved it is recommended to roughen the surface by grinding or blast cleaning. In case of metals the substrate should be given several hours time to regenerate its oxygen layer before applying WACKER® PRIMER G 719.
Since adhesion is determined by the nature of the substrate, the applied silicone elastomer and the processing parameters, proper trials are absolutely necessary.
This product is available in 0.8 kg bottles, 20 kg pails and 160 kg drums.
WACKER® PRIMER G 719 is sensitive towards humidity. In contact with moisture the liquid primer becomes turbid and the adhesive strength of the primer is impaired. WACKER® PRIMER G 719 should therefore be stored in a sealed container after usage. In addition, it is strongly recommended to stir or shake the primer horoughly before applying.
The 'Best use before end' date of each batch is shown on the product label. Storage beyond the date specified on the label does not necessarily mean that the product is no longer usable. In this case however, the properties required for the intended use must be checked for quality assurance reasons.