Thermally cured silicone coating which can be adhesively bonded without primer
AssigneeSika Technology AG
InventorsWolf-Rudiger Huck, Reto Dohner
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Abstract
A thermally cured silicon coating on a plastic, in particular a thermoplastic, can be adhesively bonded without use of an adhesive primer. Such thermally cured silicon coatings are produced by a process including: application of a silicon composition to the surfaces of a plastic or to the surface of a plastic treated with a plastic primer; air drying of the silicon composition to form a silicone film; baking at a temperature in the range from 80° C. to 200° C.; and application of a bonding agent composition to the silicone film during baking or during the phase of cooling to ambient temperature after baking.
Claims24
A method of producing a thermally cured silicone coating on a plastic, comprising the following steps:
- applying a silicone composition to the surface of a plastic or to the surface of a plastic treated with a plastics primer;
- waiting for the silicone composition to form a silicone film, wherein the waiting step comprises at least one of
- partial drying by evaporation of a solvent or solvent mixture in the silicone composition, and
- preliminary reaction among reactive constituents in the silicone composition;
- baking at a temperature between 80° C. and 200° C.;
- and
- applying an adhesion promoter composition to the silicone film during baking or during a cooling phase to ambient temperature after baking;
- wherein the silicone composition comprises an aqueous dispersion of a colloidal silica in a mixture of water and an organic solvent and at least one trialkoxysilane RSi(OR′)3 or its silanol RSi(OR′)3n(OH)n or partial condensates thereof, where
- R represents an alkyl substituent having 1-3 carbon atoms or an aryl substituent having 6 to 13 carbon atoms;
- R′ represents an alkyl substituent having 1-3 carbon atoms;
- and
- n is 1, 2 or 3.
Dependencies are inferred from the claim text.