Expandable styrene polymers comprising polymeric brominated flame-retardant
Expandable styrene polymers comprising polymeric brominated flame-retardant, wherein the polymeric brominated flame-retardant comprises at least one brominated polybutadiene block having a bromination degree between 33 and 75%, based on the double bonds in the polybutadiene block before bromination, a process for producing such expandable styrene polymers by suspension polymerization and particulate foam moldings made therefrom.
1 . An expandable styrene polymer comprising a polymeric brominated flame-retardant, wherein the polymeric brominated flame-retardant comprises 50 to 85 wt.-% of brominated polybutadiene blocks and the weight average molecular weight M w of the polymeric brominated flame-retardant is in the range from 80.000 to 180.000 g/mol, determined by Gel Permeation Chromatography according to ISO 16014-3:2012 before bromination and the polymeric brominated flame-retardant has a total bromine content in the range from 50 to 55 wt.-%, determined by elemental analysis, and comprises at least one brominated polybutadiene block having a bromination degree, determined by 1 H-NMR spectroscopy, between 59 and 75%, based on the double bonds in the polybutadiene block before bromination, wherein a styrene polymer foam prepared from the expandable styrene polymer has an average cell size is in the range from 120 to 250 μm and a thermal conductivity of from 30.6 to 34.6 mW/(m*K).
2 . The expandable styrene polymer according to claim 1 , wherein the polymeric brominated flame retardant has a total bromine content in the range from 54 to 55 wt.-%.
3 . The expandable styrene polymer according to claim 1 , wherein the polymeric brominated flame retardant is selected from a brominated styrene-butadiene-styrene triblockcopolymer.
4 . The expandable styrene polymer according to claim 1 , wherein the amount of polymeric brominated flame retardant is in the range from 0.25 to 5% by weight.
5 . The expandable styrene polymer according to claim 1 , wherein the amount of polymeric brominated flame retardant is in the range from 0.5 to 2% by weight.
6 . The expandable styrene polymer according to claim 1 , wherein the polymeric brominated flame retardant is selected from a brominated styrene-butadiene-styrene triblock copolymer S 1 —B—S 2 with a total styrene block content of 20 to 50 wt.-% and a difference in the weight average molecular weight M w between block S 1 and S 2 is less than 10.000 g/mol, determined by Gel Permeation Chromatography according to ISO 16014-3:2012 before bromination.
7 . The expandable styrene polymer according to claim 1 , wherein the at least one brominated polybutadiene-block has a 1,2-vinyl content between 50 and 95%, based on the double bonds in the polybutadiene block before bromination.
8 . The expandable styrene polymer according to claim 1 , wherein a styrene polymer foam prepared from the expandable styrene polymer has an average cell size is in the range from 149 to 192 μm.
9 . The expandable styrene polymer according to claim 1 , wherein the polymeric brominated flame retardant is selected from a brominated styrene-butadiene-styrene triblock copolymer S 1 —B—S 2 with a total styrene block content of 25 to 45 wt.-% and a difference in the weight average molecular weight M w between block S 1 and S 2 is less than 10.000 g/mol, determined by Gel Permeation Chromatography according to ISO 16014-3:2012 before bromination.
10 . A process for producing the expandable styrene polymer according to claim 1 comprising polymerization of vinylaromatic monomers in aqueous suspension in the presence of a polymeric brominated flame-retardant, wherein the polymeric brominated flame-retardant has a total bromine content in the range from 40 to 60 wt.-%, determined by elemental analysis, and comprises at least one brominated polybutadiene block having a bromination degree, determined by 1 H-NMR spectroscopy, between 59 and 75%, based on the double bonds in the polybutadiene block before bromination.
11 . A process according to claim 10 , wherein the polymerization is carried out in the presence of 0.5 to 10% by weight of athermanic particles, based on the vinylaromatic monomers.
12 . A process according to claim 10 , wherein the amount of polymeric brominated flame retardant is in the range from 0.25 to 5% by weight, based on the vinylaromatic monomers.
13 . A styrene polymer foam molding, obtained by prefoaming and welding of the expandable styrene polymer according to claim 1 .
14 . The styrene polymer foam molding according to claim 13 , wherein the average cell size is in the range from 120 to 250 μm, determined by microscopic measurement.