| 摘要 |
Consistent control of viscosity when mixing polymers, especially rubber, with additives is desirable. …<??>Based on a new approach to the estimation of when a prescribed viscosity is being attained by the mixing, the process typically comprises.… (i) deforming polymer until it is estimated to attain a first predetermined viscosity, then … (ii) adding filler and deforming the polymer-and-filler mixture until it is estimated to attain a second predetermined viscosity, then… (iii) adding oil or plasticiser, and deforming the resulting mixture until it is estimated to attain a third predetermined viscosity, then… (iv) discharging the resulting mixture from the process. …<??>Our way of estimating that each predetermined viscosity is attained is as follows: the mixing torque applied by the mixer is measured at least twice at a fixed mixer-rotor speed and corrected to a reference batch temperature; the rate of change of the torque is determined; the time, or the deforming energy, to reach the torque characteristic of the respective predetermined viscosity is predicted by extrapolation; and the deforming is continued for the predicted time or energy. …<??>In the process, optionally, at a predetermined length of time before step (iii) is completed, the other ingredients which promote cross-linking are added to the mixture, so that different batches of the product behave consistently later on. The quantity of other ingredients added may be adjusted as a further or alternative means of controlling viscosity. …<??>The ram pressure applied to the mixing chamber may be increased or decreased in response to the cyclic ram movement observed during mixing, to ensure no stagnation nor undue temperature rise. |
