Process for preparing a solventless polyorganosiloxane pellet and a waterborne dispersion of a silicone pressure sensitive adhesive base

A process for preparing a waterborne dispersion of a silicone pressure sensitive adhesive base from solventless polyorganosiloxane pellets, said process comprising:

• 1) Providing an extruder comprising a barrel having a first feed port, a second feed port, and an outlet with a die;
• heating means configured to heat the barrel;
• and a screw mechanism housed within the barrel, where the first feed port and the second feed port are configured to introduce starting materials into the extruder, the screw mechanism is capable of mixing and conveying the starting materials from the first feed port and the second feed port to the outlet, the first feed port is upstream of the second feed port, and the second feed port is upstream of the outlet;
• 2) Adding i) at least a portion of a solventless polydiorganosiloxane gum into the extruder through the first feed port, and adding ii) a solventless polyorganosilicate resin into the extruder through the second feed port, wherein said gum and said resin are added in amounts such that a weight ratio resin:gum is 2.1:1 to 5:1;
• 3) Mixing the solventless polydiorganosiloxane gum and the solventless polyorganosilicate resin in the barrel and while heating the barrel at a temperature of 200° C. to 250° C., thereby forming a mixture;
• 4) Conveying the mixture through the die at the outlet, thereby forming a strand;
• 5) Cooling the strand exiting the die, and
• 6) comminuting the strand, thereby preparing the solventless polyorganosiloxane pellets;
• 7) Feeding into a dispersing apparatus, starting materials comprising the pellets prepared in step 6);
• optionally additional polydiorganosiloxane gum in an amount sufficient to adjust the resin:gum ratio to 0.4:1 to 3:1;
• a surfactant selected from the group consisting of an anionic surfactant, a nonionic surfactant, and a combination thereof;
• and water;
• with the proviso that the surfactant does not include sulfonic acids and their salt derivatives, long chain carboxylic acid surfactants and their salts, fatty acid amines and amides and their salts and derivatives, alkylglucosides, and linear silicone polyethers;
• and
• 8) Mixing and heating the starting materials from step 7) in the dispersing apparatus;
• thereby producing the aqueous dispersion of the silicone pressure sensitive adhesive base.