Method for producing functionalized thermoplastic elastomers

A process for preparing a functionalized thermoplastic elastomer based on particulate graft substrates selected from the group consisting of:

• (i) olefin block copolymers comprising 80 to 98 mass-% of ethylene- and 2 to 20 mass-% of C3- to C12-olefin units;
• (ii) semi-crystalline copolymers of the composition 50 to 98 mass-% of propylene- and 2 to 50 mass-% of ethylene and/or C4- to C12-olefin and/or C4- to C12-diene units, and
• (iii) cross-linked styrene/olefin/styrene block copolymers or cross-linked styrene/olefin block copolymers,
• wherein in a fluid mixing reactor, is added:
• 0.1 to 15 mass parts of α,β-ethylenically unsaturated compounds containing at least one functional monomer or a monomer mixture containing the at least one functional monomer, wherein the at least one functional monomer contains functional groups,
• 0.01 to 10 mass parts of at least one initiator forming free radicals with a 1-hour half-life temperature (THWZ/1h) between 50 and 200°, and
• 100 mass parts of the particulate graft substrate;
• wherein the unsaturated compounds, the at least one initiator and particulate graft substrate are polymerized at reaction temperatures between 40° C. and the melting or softening temperature of the particulate graft substrate for a reaction time between 10 and 200 min in a solid-fluid phase, wherein a graft product having a grafted functional monomer is produced by such a solid state functionalization, which is used as a starting component for further processing, wherein during further processing:
• 100 mass parts of the graft product is mixed with:
• (i) between 0.1 and 60 mass parts of at least one other functional monomer;
• or (ii) between 0.1 and 60 mass parts of another monomer mixture containing the at least one other functional monomer and between 0.01 and 20 mass parts of at least one other initiator forming free radicals with a 1-hour half-life temperature (THWZ/1h) 80-240° C. producing a mixture;
• the mixture together with 100 to 4000 mass parts of an unmodified olefin elastomer, are continuously fed into an intake area of a reaction extruder via metering devices,
• reactive extrusion from the reactor extruder is carried out at temperatures above melting or softening point of the unmodified olefin elastomer, and
• the functionalized thermoplastic elastomer is continuously discharged from the reaction extruder.