Abstract: The process for recycling and de-vulcanizing vulcanized rubber comprises the steps of: grinding said rubber in a mill in order to shred it into particles having a size substantially comprised between 5 and 15 mm; introducing the particles in an initial section of a two-screw co-rotating extruder having a length 64 times or more the external diameter of the screws, mixing the particles within the extruder, which is kept at a temperature comprised between 35 and 350° C., due to the screw rotation at a speed comprised between 15 and 300 rpm; and obtaining an extruded product formed by de-vulcanized rubber.

Abstract: The process for recycling and de-vulcanizing vulcanized rubber comprises the steps of: grinding said rubber in a mill in order to shred it into particles having a size substantially comprised between 5 and 15 mm; introducing the particles in an initial section of a two-screw co-rotating extruder having a length 64 times or more the external diameter of the screws, mixing the particles within the extruder, which is kept at a temperature comprised between 35 and 350° C., due to the screw rotation at a speed comprised between 15 and 300 rpm; and obtaining an extruded product formed by de-vulcanized rubber.

Abstract: The method for the continuous production of a composition comprising rubber (20), hydrocarbon resin (22), and solvent (26) provides for the use of a dual-screw extruder (10), for example, a co-rotating dual-screw extruder. Preferably, at least a fraction of the solvent (26) is added at a point of the extruder (10) that is downstream of the initial section, for example, at a distance of at least 4 D from the initial section of the extruder (10).

Abstract: The process for the continuous production of a composition comprising rubber (20), a hydrocarbon resin (22) and a solvent (26) provides for the use of at least two two-screw extruders (10a, 10b) placed in series. These extruders may be of the contrarotating type or, preferably, co-rotating.

Abstract: The mixing element has a central hole for keying to the shaft of the screw and an outer profile which can be produced as a result of the removal of material from a circular element along at least one arc of its Outer portion by cutting performed by a point-like element rotating around a circle with a diameter equal to that of the circular element. The point-like element and the circular element rotate in the same direction and at the same speed and the centers of the circular element and of the circle are spaced apart by a distance less than their diameter. During a portion of the cutting process, the distance between the centers of the circular element and of the circle is reduced so that the portion of the outer profile which is correspondingly cut is recessed.

Abstract: The device for extracting undesired substances, such as volatile components of low molecular weight, free gases, liquids and the like, from the cylinder of an extruder, in particular for thermoplastic materials, includes a casing defining internally an oblong cavity communicating at one end with the internal cavity of the extruder; at least one screw mounted for rotation in the oblong cavity, substantially parallel to the longitudinal axis thereof; and vacuum means for creating a depression in the oblong cavity. The longitudinal axis of the oblong cavity forms an angle of between 0° and −45° with a horizontal plane passing through the axis of the cylinder of the extruder.

Abstract: The reduction gear unit, particularly for use in twin-screw extruders comprises an input shaft (10), a first output shaft (12) and a second out put shaft (14) located parallel to and close to each other and associate with a respective worm screw, and a first gear train (16) and a second gear train (18) for connecting the input shaft (10) to the first output shaft (12) and to the second output shaft (14) respectively. The second output shaft (14) is long than the first output shaft (12) and is connected to the second gear train (18) by a part which is not alongside the first output shaft (12). Moreover, the input shaft (10) has a torsionally resilient portion (40) between its parts connected to the first gear train (16) and the second gear train (18) respectively.