Mechanical inversion process for marking silicone oil-in-water emulsions

A method of making a silicone oil-in-water emulsion comprising the steps of:

• (i) forming a homogeneous oil phase containing a silicone gum, a silicone rubber, a silicone elastomer, a silicone resin, or a mixture thereof;
• the silicone in the homogenous oil phase having a viscosity of at least 100,000,000 (100 million) centistoke (mm2/s) to 5,000,000,000 (5 billion) centistoke (mm2/s);
• (ii) mixing one or more surfactants with the homogenous oil phase;
• (iii) adding water to the homogenous oil phase to form a water-in-oil emulsion containing a continuous phase and a dispersed phase, the water being added in an amount of about 0.5-10 percent by weight based on the weight of the silicone in the homogenous oil phase;
• (iv) applying high shear to the water-in-oil emulsion in a twin-screw extruder having a length to diameter L/D ratio of at least 15, to cause inversion of the water-in-oil emulsion to an oil-in-water emulsion;
• and (v) diluting the oil-in-water emulsion by the addition of water;
• the method being carried out in the absence of a solvent other than solvents present in the silicone gum, silicone rubber, silicone elastomer, or silicone resin in (i).