Process and a device assembly useful for producing a molded silicone rubber product from liquid silicone rubber composition via injection molding

A method useful for producing a molded silicone rubber product M1 via injection molding comprising:

• a) feeding into a base feed line a liquid silicone rubber base composition A1 which does not contain a catalyst, and which comprises:
• at least one organopolysiloxane A containing at least 2 alkenyl groups bonded to silicon atoms per molecule,
• optionally at least one organopolysiloxane B containing at least 2 silicon-bonded hydrogen atoms per molecule B;
• and optionally at least 3 silicon-bonded hydrogen atoms per molecule B,
• optionally, at least one filler C,
• optionally at least one inhibitor E for hydrosilylation vulcanizing reaction, and
• optionally at least one additive F,
• b) feeding into a separate catalyst feed line a catalyst masterbatch C1 comprising at least one platinum-based catalyst D,
• c) feeding into a separate feed line an inhibitor masterbatch E1 comprising at least one inhibitor E for hydrosilylation vulcanizing reaction,
• d) feeding either into a separate feed line or into any feedline containing the catalyst masterbatch C1 or the inhibitor masterbatch E1 at least one crosslinker XL which is an organopolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule when it is a linear or a cyclic polymer or at least two silicon-bonded hydrogen atoms per molecule when it is a branched polymer,
• e) optionally feeding into a separate additive feed line at least one additive F,
• f) directing said liquid silicone rubber base composition A1, said catalyst masterbatch C1, said crosslinker XL, said inhibitor masterbatch E1 and optionally said additive F either into a mixing tank prior to directing the resulting mixture into a barrel of an injection machine or directly into said barrel to obtain a crosslinkable liquid silicone rubber composition A3 comprising:
• 1) At least one organopolysiloxane A containing at least 2 alkenyl groups bonded to silicon atoms per molecule,
• 2) optionally at least organopolysiloxane B containing at least 2 silicon-bonded hydrogen atoms per molecule B;
• and optionally at least 3 silicon-bonded hydrogen atoms per molecule B,
• 3) optionally, at least one filler C,
• 4) at least one platinum-based catalyst D,
• 5) at least one inhibitor E for hydrosilylation vulcanizing reaction,
• 6) at least one crosslinker XL which is an organopolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule when it is a linear or a cyclic polymer or at least two silicon-bonded hydrogen atoms per molecule when it is a branched polymer, and
• 7) optionally at least one additive F;
• and
• wherein the added amounts in said crosslinkable liquid silicone rubber composition A3 of said platinum-based catalyst D and said inhibitor E for hydrosilylation vulcanizing reaction are controlled and adjusted so as to get a molar ratio of the inhibitor E for hydrosilylation vulcanizing reaction to platinum atom of the platinum-based catalyst D which ranges from 0.1 to 900 (0.1:1 to 900:1), optionally from 10 to 900 (10:1 to 900:1), and optionally from 20 to 250 (20:1 to 250:1),
• g) directing said crosslinkable liquid silicone rubber composition A3 into a mold which is installed in a molding press and curing it, optionally by heating at a temperature ranging from 80° C. to up to 220° C., so as to obtain a molded silicone rubber product M1.