EXPANDABLE STYRENE POLYMERS COMPRISING POLYMERIC BROMINATED FLAME-RETARDANT

Abstract

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.

Claims

1.-12. (canceled)

13. An expandable styrene polymers comprising polymeric brominated flame-retardants, wherein the polymeric brominated flame-retardant comprises 50 to 85 wt.-% of brominated polybutadiene blocks and the weight average molecular weight M.sub.w of the polymeric brominated flame-retardant is in the range from 80.000 to 180.000 g/mol, determined 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 40 to 60 wt.-%, determined by elemental analysis, and comprises at least one brominated polybutadiene block having a bromination degree, determined by .sup.1H-NMR spectroscopy, between 59 and 75%, based on the double bonds in the polybutadiene block before bromination.

14. The expandable styrene polymers according to claim 13, wherein the polymeric brominated flame retardant has a total bromine content in the range from 50 to 55 wt.-%.

15. The expandable styrene polymers according to claim 13, wherein the polymeric brominated flame retardant is selected from a brominated styrene-butadiene-styrene triblockcopolymer.

16. The expandable styrene polymers according to claim 13, wherein the amount of polymeric brominated flame retardant is in the range from 0.25 to 5% by weight.

17. The expandable styrene polymers according to claim 13, wherein the amount of polymeric brominated flame retardant is in the range from 0.5 to 2% by weight.

18. The expandable styrene polymers according to claim 13, wherein the polymeric brominated flame retardant is selected from a brominated styrene-butadiene-styrene triblock copolymer S.sub.1—B—S.sub.2 with a total styrene block content of 20 to 50 wt.-% and a difference in the weight average molecular weight M.sub.w between block S.sub.1 and S.sub.2 is less than 10.000 g/mol, determined by Gel Permeation Chromatography according to ISO 16014-3: 2012 before bromination.

19. The expandable styrene polymers according to claim 13, 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.

20. A process for producing the expandable styrene polymers according to claim 13 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 .sup.1H-NMR spectroscopy, between 59 and 75%, based on the double bonds in the polybutadiene block before bromination.

21. A process according to claim 20, wherein the polymerization is carried out in the presence of 0.5 to 10% by weight of athermanic particles, based on the vinylaromatic monomers.

22. A process according to claim 20, wherein the amount of polymeric brominated flame retardant is in the range from 0.25 to 5% by weight, based on the vinylaromatic monomers.

23. A styrene polymer foam moldings, obtained by prefoaming and welding of expandable the styrene polymers according to claim 13.

24. Styrene polymer foam moldings according to claim 23, wherein the average cell size is in the range from 120 to 250 μm, determined by microscopic measurement.

Description

EXAMPLES

[0036] Hereinafter, the present invention is described in more detail and specifically with reference to the Examples, which however are not intended to limit the present invention.

[0037] Brominated Styrene-Butadiene-Styrene triblock copolymers Br—SBS

[0038] Styrene-Butadiene-Styrene triblock copolymers SBS with 33 wt.-% polymerized styrene units and 67 wt.-% of polymerized butadiene units (thereof 78% wt. 1,2-units and 22 wt.-% 1,4-units) and a total molecular weight M.sub.w of 130.000 g/mol (determined by GPC according to ISO 16014-3: 2012 relative to polystyrene standards in 25° C. in THF prior to the bromination) were brominated according to WO 2007/058736 with different molar ratios of tetraethylammonium tribromide to obtain the brominated SBS block copolymers with the characteristics shown in Table 1.

[0039] Total bromine content in the Br—SBS triblock copolymer was determined by combustion and argentometric analysis.

[0040] The degree of bromination of the non-aromatic double bonds was determined by .sup.1H-NMR spectroscopy by comparing integrated areas of signals due to residual double bond protons and protons for brominated polybutadiene.

[0041] The weight-average molar masses M.sub.w were determined by Gel permeation chromatography methods (GPC) according to ISO 16014-3: 2012 on polystyrene-Gel columns from company Polymer Labs of the type Mixed B, with monodisperse polystyrene standards and tetrahydrofu-ran as eluent at room temperature with 20° C.

TABLE-US-00001 TABLE 1 Br-SBS triblock copolymers: Br-SBS triblock Bromine content in Br-SBS Degree of copolymer [wt.-%] bromination FR 59 54% 59% FR 62 55% 62% FR 78 61% 78% FR 96 65% 96% FR 100 66% 100% 

Examples 1 and 2 and Comparative Examples C1-C3

[0042] Preparation of Expandable Polystyrene (White EPS)

[0043] 15 g of benzoyl peroxide (Perkadox L-W75 from Nouryon), 115 g of dicumyl peroxide (Perkadox® BC—FF from Nouryon) and the amount of Br—SBS triblock copolymer indicated in table 2 were dissolved in 22.8 kg of styrene. This organic phase was entered in 17.5 kg of demineralized water in a 55 l stirred vessel. The aqueous phase contained in addition 36 g of magnesium pyrophosphate (prepared from sodium pyrophosphate and magnesium sulfate). The mixture was heated under stirring to 104° C. within 110 minutes and then heated to 134° C. within 255 minutes. 105 minutes after reaching 80° C., 73 g of a 2 wt.-%-solution of emulsifier E30 (Mersolat® H40 from the company Lanxess) were metered in. After further 46 minutes, 1.21 kg of pentane (Exxsol® pentanes 80 from the company ExxonMobil) were metered in. Stirring is then continued for 1 h hour at the final temperature of 134° C. to complete polymerization. The expandable polystyrene obtained is decanted off and dried.

[0044] Then the beads were coated with 0.3% (w/w) of a mixture of 60% (w/w) glycerol tristearate (Soft enol® 3168 from the company 101 Oleo) 30% (w/w) glycerol monostearate (Softenol® 3995 from the company 101 Oleo) and 10% (w/w) zinc stearate (Zincum® 5 from Baerlocher).

Examples 3 and 4 and Comparative Examples C4-C6

[0045] Preparation of Graphite-Containing Expandable Polystyrene (Grey EPS) 22.4 g dicetylperoxodicarbonate (Perkadox® 24-FL from Nouryon), 11.3 g tert.-butylethylhexanoat (Trigonox® 21S from Nouryon), 100 g of dicumyl peroxide (Perkadox® BC—FF from Nouryon), 825 g graphite (UF 99.5 from Graphit Kropfmuhl) and the amount of Br—SBS triblock copolymer indicated in table 2 were dissolved in 16.5 kg of styrene. This organic phase was entered in 20.8 kg of demineralized water in a 551 stirred vessel. The aqueous phase contained in addition 50 g of magnesium pyrophosphate (prepared from sodium pyrophosphate and magnesium sulfate). The mixture was heated under stirring to 94° C. within 90 minutes and then heated to 135° C. within 254 minutes. 95 minutes after reaching 80° C., 73 g of a 2 wt.-%-solution of emulsifier E30 (Mersolat® H40 from the company Lanxess) were metered in. After further 110 minutes, 1.25 kg of pentane (Exxsol® Pentane 80 from the company ExxonMobil) were metered in. Stirring is then continued for 1 h hour at the final temperature of 135° C. to complete polymerization. The expandable polystyrene obtained is decanted off and dried.

[0046] Then the beads were coated with 0.3% (w/w) of a mixture of 60% (w/w) glycerol tristearate (Softenol® 3168 from the company 101 Oleo) 30% (w/w) glycerol monostearate (Softenol® 3995 from the company 101 Oleo) and 10% (w/w) zinc stearate (Zincum® 5 from Baerlocher).

TABLE-US-00002 TABLE 2 Amount of Br-SBS triblock copolymer used in Examples 1 to 4 and Comparative Examples C1 to C6 Example BR-SBS Amount [g] 1 FR 59 235 g 2 FR 62 235 g C1 FR 78 213 g C2 FR 96 199 g C3 FR 100 195 g 3 FR 59 277 g 4 FR 62 277 g C4 FR 78 251 g C5 FR 96 235 g C6 FR 100 230 g

[0047] The Production of Particle Foam Molding

[0048] The blowing agent-containing beads from Examples 1 to 4 and Comparative Examples C1 to C6 were pre-foamed in flowing steam. After 12 h of storage the prefoamed particles were weld-ed in a closed mold with steam to give particle foam moldings having a density of about 15 kg/m.sup.3 for white EPS and about 20 kg/m.sup.3 for grey EPS. The results are summarized in table 3.

[0049] The determination of the fire behavior according to EN 13238 on 20 mm thick samples was carried out after conditioning according to EN 11925-2 with 15 s edge inflammation.

[0050] The thermal conductivity of the samples was determined according to EN 12667 with a guarded hot plate apparaturs with 50 mm thick samples at a mean test temperature of 10° C.

[0051] The average cell size was determined by microscopic measurement.

[0052] Comparative Examples C1 to C3, which comprise Br—SBC block copolymers with a degree of bromination of at least 78% as flame retardant show a lower cell size and higher thermal conductivity compared with Examples 1 and 2. The same effect is demonstrated for foam moldings made from graphite-containing EPS, when comparing Comparative Examples C4 to C6 with Examples 3 and 4.

TABLE-US-00003 TABLE 3 Results of the analysis of the particle foam moldings Fire class Thermal Average Density according conductivity cell size Example [kg/m.sup.3] to EN 13501-1 [mW/(m*K)] [μm] 1 20.1 E 34.4 192 2 20.2 E 34.6 150 C1 19.6 E 36.4 105 C2 21.2 E 36.0 84 C3 19.7 E 36.8 88 3 16.9 E 30.6 157 4 15.5 E 30.9 149 C4 16.1 E 31.8 108 C5 15.0 E 32.3 108 C6 14.6 E 32.1 110