Process for preparing silicone rubber composition

A process for preparing a silicone rubber composition, comprising the steps of:

• (A) mixing
• a base material component (A-1), which is obtained by mixing an organopolysiloxane and a reinforcing silica and then heating the resulting mixture at a temperature of 100.degree. to 250.degree. C. for 1 to 6 hours, with
• at least one component (A-2) selected from the group consisting of an aminosilane compound represented by the following general formula (1):
• (R.sup.1).sub.3 Si [N (R.sup.2).sub.2 ] (1)
• wherein a plurality of R.sup.1 may be the same or different and each represent a substituted or unsubstituted monovalent hydrocarbon group, and a plurality of R.sup.2 may be the same or different and each represent a substituted or unsubstituted monovalent hydrocarbon group;
• and an aminosilane compound represented by the following general formula (2):
• (R.sup.1).sub.2 Si [N (R.sup.2).sub.2 ].sub.2 ( 2)
• wherein a plurality of R.sup.1 may be the same or different and are as defined above, and a plurality of R.sup.2 may be the same or different and are as defined above;
• and allowing them to react;
• and
• (B) heating the reaction mixture obtained in the step (A) under normal pressure or reduced pressure to remove an unreacted aminosilane compound and a by-product amine, contained in the reaction mixture.