Method for incorporating solids for producing thermally sensitive polymers in a planetary roller extruder, characterized in that a) the planetary roller extruder consists of a filling and dispersing zone operated atmospherically and comprising at least one roller cylinder (1, 2) and of a downstream venting and cooling zone operated under reduced pressure and comprising at least one further roller cylinder (3, 4), b) the at least one roller cylinder (1, 2) of the filling and dispersing zone is separated from the at least one roller cylinder (3, 4) of the venting and cooling zone via a hold-up ring which is located between the roller cylinders (1, 2, 3, 4) and has a free cross section selected such that the melt held up there provides gas- impervious separation of the filling and dispersing zone from the venting and cooling zone, allowing the two zones to be operated with different pressures, c) the polymers are supplied to the planetary roller extruder in a plastified state, d) the plastified polymers are fed into the at least one roller cylinder (1, 2) of the filling and dispersing zone, and specifically within the first third of the roller cylinder, e) solids such as thermal crosslinkers are added to the plastified polymers downstream of the addition of the plastified polymers in the filling and dispersing zone, in particular by means of a lateral screw feeder, via an opening of the at least one roller cylinder (1, 2), f) the solids are dispersed in the plastified polymers in the filling and dispersing zone, g) the solids comprise at least thermal crosslinkers which are able to crosslink the plastified polymers for the purpose of increasing the molar mass of the polymers, h) the initial temperatures of the central spindle and of the at least one roller cylinder (1, 2) within the filling and dispersing zone are established such that there is no gelling of the plastified polymers blended with the thermal crosslinkers, which thus remain flowable, i) the at least one roller cylinder (3, 4) and more particularly all the roller cylinders of the venting and cooling zone are fitted with a number of planetary spindles which is less than 75% of the maximum possible number of planetary spindles, j) the at least one roller cylinder (3, 4) of the venting and cooling zone possesses at least one opening (10, 11) in the casing via which the plastified polymers blended with the solids, preferably with thermal crosslinkers, are freed from air and any further volatile substances by means of reduced pressure, k) the at least one opening (10, 11) for application of reduced pressure in the venting and cooling zone has an area of at least 5% of the area within this region that is over-rolled by the planetary spindles, l) the mixture of plastified polymers and solids, preferably thermal crosslinkers, is supplied, more preferably in-line, to a coating assembly. a) the planetary roller extruder consists of a filling and dispersing zone operated atmospherically and comprising at least one roller cylinder (1, 2) and of a downstream venting and cooling zone operated under reduced pressure and comprising at least one further roller cylinder (3, 4), b) the at least one roller cylinder (1, 2) of the filling and dispersing zone is separated from the at least one roller cylinder (3, 4) of the venting and cooling zone via a hold-up ring which is located between the roller cylinders (1, 2, 3, 4) and has a free cross section selected such that the melt held up there provides gas- impervious separation of the filling and dispersing zone from the venting and cooling zone, allowing the two zones to be operated with different pressures, c) the polymers are supplied to the planetary roller extruder in a plastified state, d) the plastified polymers are fed into the at least one roller cylinder (1, 2) of the filling and dispersing zone, and specifically within the first third of the roller cylinder, e) solids such as thermal crosslinkers are added to the plastified polymers downstream of the addition of the plastified polymers in the filling and dispersing zone, in particular by means of a lateral screw feeder, via an opening of the at least one roller cylinder (1, 2), f) the solids are dispersed in the plastified polymers in the filling and dispersing zone, g) the solids comprise at least thermal crosslinkers which are able to crosslink the plastified polymers for the purpose of increasing the molar mass of the polymers, h) the initial temperatures of the central spindle and of the at least one roller cylinder (1, 2) within the filling and dispersing zone are established such that there is no gelling of the plastified polymers blended with the thermal crosslinkers, which thus remain flowable, i) the at least one roller cylinder (3, 4) and more particularly all the roller cylinders of the venting and cooling zone are fitted with a number of planetary spindles which is less than 75% of the maximum possible number of planetary spindles, j) the at least one roller cylinder (3, 4) of the venting and cooling zone possesses at least one opening (10, 11) in the casing via which the plastified polymers blended with the solids, preferably with thermal crosslinkers, are freed from air and any further volatile substances by means of reduced pressure, k) the at least one opening (10, 11) for application of reduced pressure in the venting and cooling zone has an area of at least 5% of the area within this region that is over-rolled by the planetary spindles, l) the mixture of plastified polymers and solids, preferably thermal crosslinkers, is supplied, more preferably in-line, to a coating assembly.