Method for producing flame-proofed thermoplastic molding compounds

摘要

The invention relates to a method for producing thermoplastic molding compounds, comprising: A) 40 to 99 wt % of at least one thermoplastic polymer, B) 1 to 60 wt % of a flame-proofing agent component containing an expandable graphite, and C) 0 to 60 wt % of further additives, by melt-mixing components A), B) and C) in a screw-type extruder, wherein the screw-type extruder, along the feed direction, comprises, in the following order, at least one dosing zone, a plastifying zone, a homogenizing zone, a second dosing zone, and a discharge zone, in that the dosing takes place into the screw-type extruder having the length L, wherein the length L is defined as the section starting with the first dosing unit for adding components A, B and/or C and ending, in the feed direction, at the discharge opening, a melt is generated after adding components A, B and C in the range of 0 liter to 0.15 liter in a first method step in the presence of component B1), and in a second method step, after the addition of component B1) in the range of 0.5 liter to 0.95 liter, component B1) is mixed into said melt, wherein said method offers technical advantages.

主权项

1. A process for the preparation of thermoplastic molding materials comprising:
A) from 40 to 99% by weight of at least one thermoplastic polymer, B) from 1 to 60% by weight of a flameproofing component comprising B1) an expandable graphite, and C) from 0 to 60% by weight of further additives,the percentages by weight being based in each case on the total weight of the components A) to C) and together giving 100% by weight,by mixing melts of the components A), B) and, if present, C) in a screw extruder, the screw extruder comprising at least one metering zone, one plasticating zone, one homogenization zone, one second metering zone and one discharge zone in this sequence along the conveying direction,wherein the metering into the screw extruder having the length L, the length L being defined as the section beginning at the first metering means for the addition of components A, B and/or C and ending, in the conveying direction, at the exit opening, following addition of components A, B and C in the region from 0 L to 0.15 L in a first process step in the absence of component B1) a melt is produced, and in a second process step after addition of the component B1) in the region from 0.7 L to 0.85 L the mixing of component B1) into this melt is carried out.