Rubber composition manufacturing method, tire manufacturing method, and rubber composition manufacturing apparatus

A rubber composition manufacturing method comprising;

• a first operation in which at least rubber, silica, and silane coupling agent are kneaded in an internal kneader while kneading temperature is controlled so as to be below a temperature lower limit for a coupling reaction between the silica and the silane coupling agent to proceed;
• and a second operation in which at least the rubber, the silica, and the silane coupling agent are kneaded in the internal kneader at not less than the temperature lower limit for the coupling reaction between the silica and the silane coupling agent to proceed, wherein
• the internal kneader comprises a kneading chamber, a neck which is located above the kneading chamber, and a ram which is capable of moving vertically through a space within the neck;
• for at least a portion of time during which the second operation is being carried out, a compressed gas is delivered to the kneading chamber while the ram is in a nonpressing state;
• the internal kneader comprises a rotor at the kneading chamber;
• in the first operation, rotational speed of the rotor is controlled by means of proportional integral differential control to cause the kneading temperature to be a first target temperature;
• the first target temperature is less than 140° C.;
• for the at least the portion of the time during which the second operation is being carried out, rotational speed of the rotor is controlled by means of proportional integral differential control to cause the kneading temperature to be a second target temperature;
• and
• the second target temperature is not less than 140° C.