Shelf-stable one-part room temperature vulcanizing fluorosilicone compositions

A method for continuously producing a shelf stable room-temperature vulcanizable composition from an extruder having a first supply port, an exit port, and a second supply port located along said extruder between said first supply port and said exit port, said method comprising the steps of:

• (1) supplying a base composition (A) to said extruder at said first supply port and maintaining the temperature of the base composition between 100.degree. and 200.degree. C., said base composition (A) comprising:
• (A1) 100 parts by weight of a silanol terminated fluorosilicone having the formula HO(RR.sup.1 SiO).sub.x OH, wherein each R is a monovalent hydrocarbon radical free of aliphatic unsaturation containing from 1 to about 8 carbon atoms, each R.sup.1 is a fluorinated monovalent hydrocarbon free of aliphatic unsaturation having from 1 to about 8 carbon atoms and x varies so that (A1) has a viscosity of about 600 to about 300,000 cps at 25.degree. C.;
• (A2) from about 3 to about 25 parts by weight based upon (A1) of a silica filler having a surface area of about 100 to 300 m.sup.2 /gm in an untreated state,
• (A3) up to about 200 parts by weight based upon (A1) of finely divided Fe.sub.2 O.sub.3 having an average particle size ranging from about 0.05 to about 5 microns;
• (2) adding a catalyst solution (B) to said extruder at said second supply port, said catalyst solution (B) comprising:
• (B1) up to about 0.5 parts by weight based upon 100 parts of the base composition (A) of a tin based catalyst;
• and
• (B2) from about 2 to about 15 parts by weight based upon 100 parts of the sum of (A1), (A2) and (A3) of at least one acetoxy cross-linking agent.