New generation of aluminium hydroxide flame retardant filler for the wire and cable industry Dr. Reiner Sauerwein Nabaltec GmbH
Overview Introduction New ATH quality product characteristics Powder handling properties during compounding - conveyance - feeding / metering - dust behaviour - filler uptake Compound properties Options for high performance ATH - low process costs of standard LSFOH - new compound developments Conclusions
Introduction Market Share of LSFOH PE-consumption in 2001 Total 325.000 tons for Western Europe MD/HDPE 18% LLDPE 9% XPE 41% Germany LDPE Schwandorf 15% LSFOH 12% More than 70.000 tons of ATH in PE-based LSFOH compounds Cellular PE 5% A. Reynolds, Raw materials usage in the European cable industry ; Cables 2002
Introduction - cost factors of LSFOH cable production Raw material costs polymers ATH additives (stabilizers, coupling agents,...) Process costs Compounding costs energy consumption compound throughput Extrusion costs energy consumption extrusion speed / output Reduction of process costs / unit units / time powder handling ATH showing good conveyance good metering / dosing fast uptake in polymer melt Compounds high melt flow good rheology good extrusion compound performance
Powder handling during Compounding - problems Common Solutions low bulk density dust emission flowability / conveyance A) Physical Densification - higher filler mass throughput during volumetric feeding - better flow properties, - non consistent bulk density during air suction/pressure conveyance B) Organic Coating - good flow - low viscosities in compounds, - sometimes poor mechanical properties - poor electrical insulation properties (high water uptake)
New Solution Apyral 40CD - characteristics wateruptake (ml/g) 1 0,8 0,6 0,4 0,2 0 0 10 20 30 40 50 60 t (min) d50 (µm) 1.2-1.5 1.0 1.3 BET (m 2 /g) 3 4.5 3.5-5 Bulk density (g/l) 400 400 Moisture (%) 0.2 0.2 Oil absorption (%) Water uptake (ml/g) 26-30 0.6 0.7 19-23 0.4 0.5 Apyral 40CD shows extremely low oil absorption for a fine precipitated ATH quality!!! No coating! No densification! Water Uptake measured according to Baumann (in line with DIN 53495) Significantly lower water uptake of Apyral 40 CD!!!
Compounding critical process parameters delivery/ storage/ input of raw materials Silo-truck day-bin preparation of raw material Silo flow dosing flow bulk density dry mixing BB-station flow dustemission flow consistency of bulk density bulk density compounding Pipe conveyance -air suction -air pressure compound
Conveyance trial BB station 1 Air suction conveyance: - Length 60m, - pipe diameter 60mm - vertical and horizontal elements - 90 corners: 11 450 400 2 Receiving set bulk density 350 300 250 200 Apyral 40CD Apyral 40D CD = consistent density 3 BB Vibration bottom 1 2 3
Flow behaviour feeding during continuous compounding Gravimetric dosing of ATH via two dosing units within a buss-kneader-line (fixed mass flow) 15-20% lower screw speed needed for Apyral 40CD!!! screw speed (rpm) 500 400 300 200 100 0 D1 dosing unit D2
Dust behaviour measurement according to DIN 33897 part 2 Benefits of this method Simulation of discharge-, filling- and conveyance- processes Selective sampling and determination of breathable (S E ; Def. acc. to DIN EN 481) and alveoli passing dust (S A ) High sensitivity and reproduce ability Further analyses of dust particles possible Lit: Das Staubungsverhalten quarzfeinstaubhaltiger Produkte ; Gefahrstoffe-Reinhaltung der Luft 60 (2000) Nr. 5, Mai. Apparatus ; with the kind permission of IGF Institut für Gefahrstoff-Forschung der Bergbau-Berufsgenossenschaft
Dust behaviour results Filler S A (mg/kg) S E (mg/kg) Apyral 40CD < 0.3* 100 Apyral 40D < 0.3* 118 TiO 2 (d50 = 1µm) 1.04 88 BaSO 4 (d50 = 8µm) 8.7 205 Carbon black (d50 = 1.7µm) 39.8 704 *non traceable Apyral 40CD shows a 15-20% reduction of breathable dust compared to standard ATH qualities as e.g. Apyral 40D!!! Compared to other fillers, both ATH qualities are very low in S A - dust and low to medium with regard to S E dust!
Compounding behaviour - Power Consumption of Buss-kneader MDK 46 Ø = 2,9kW Ø = 2,7kW Electrical power uptake of screw motor Compounding behaviour of Apyral 40D is good Compounding behaviour of Apyral 40CD better than Apyral 40D
Compound properties EVA EVA (19%VA) ; Aminosilane coupled 60 wt.-% ATH 14 Tensile strength 250 Elongation at break Tensile strength (MPa) 12 10 8 6 4 Elongation at break (%) 200 150 100 50 2 0 0 Compounding in batch dispersion kneader ; specimens cut out of compression moulded plates MVI (cm 3 /10min) 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 Melt flow index 160 C 1 2 190 C No impact on mechanics! 30% increase in MFI for Apyral 40CD!!!
12 Compound properties PE / EVA Tensile strength PE/EVA ; Vinylsilane coupled 60 wt.-% ATH 300 Elongation at break 10 250 Tensile strength (MPa) 8 6 4 Elongation at break (%) 200 150 100 2 50 0 Continuous compounding in Buss-co-kneader MDK46 ; specimens cut out of extruded tapes. MVR (cm 3 /10min) 10 8 6 4 2 0 0 Melt flow index 160 C No impact on mechanics! More than 50% increase in MFI for Apyral 40CD!!!
Flame Retardant Properties Limiting Oxygen Index = LOI ASTM D 2863-77 LOI of Apyral 40CD containing compounds slightly enhanced LOI (%O2) 40 39 38 37 36 35 34 33 EVA (19%VA) Aminosilane LOI (%O2) 40 39 38 37 36 35 34 33 PE/EVA Vinylsilane 32 32
Melt Flow as a function of silane content Good melt flow properties options MVR (cm 3 /10min) 5,5 5 4,5 4 3,5 3 2,5 EVA (19%VA) ; 60 wt.-% ATH 2 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 Aminosilane (%) Low process costs for standard LSFOH compounds Higher extrusion speeds High productivity High competitiveness against alternative FR - compound Highly filled and flame retarded LSFOH compounds Freedom to increase filler level Freedom to add synergistic (mineral) additives
Melt Rheology PE / EVA PE/EVA ; 60 wt.-% ATH ; Vinylsilane coupled Capillary Rheometer ; 150 C Shear Viscosity η s (Pas) 10000 1000 100 10 100 1000 10000 Apyral 40CD shows lower compound viscosity than Apyral 40D over the whole shear velocity range Shear Velocity dγ/dt (s -1 )
Extrusion properties PE / EVA Set-up Extruder with BM-screw at 30 rpm; 0,5mm 2 copper, round; Diameter tip 0,85mm Diameter die 1,4mm Line speed: 650 m/min p (bar) 900 850 800 750 700 T m = 168 C p m = 800bar T m = 151 C p m = 740bar 170 160 150 140 130 T ( C) Melt pressure and melt temperature of Apyral 40CD is lower than for Apyral 40D freedom to enhance line speed by extruder screw speed!!!
Melt Flow as a function of silane content Good melt flow properties options MVR (cm 3 /10min) 5,5 5 4,5 4 3,5 3 2,5 EVA (19%VA) ; 60 wt.-% ATH 2 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 Aminosilane (%) Low process costs for standard LSFOH compounds Higher extrusion speeds High productivity High competitiveness against alternative FR - compounds Highly filled and flame retarded LSFOH compounds Freedom to increase filler level Freedom to add synergistic (mineral) additives
EVA 65wt.-% filler: mechanical properties Elongation at break (%) Tensile strength (MPa) 160 155 150 145 140 135 130 125 120 14,5 14 13,5 13 12,5 12 11,5 11 10,5 ATH ATH+AOH ATH+AOH +ZnB Bi-blends of Apyral 40CD and Apyral AOH180 (=AOH) and... tri-blends with Zinc borate (=ZnB) show good balanced physical properties at 65wt.-% filler content!!! Compounding in batch dispersion kneader ; specimens cut out of compression moulded plates
EVA 65wt.-% filler: LOI ; MVR 50 ATH ATH+AOH ATH+AOH +ZnB LOI = 43,2 %O 2 PHRR = 170 kw/m 2 TTI = 78 sec 48 46 LOI (%O2) 44 42 40 38 MVR cm 3 / 10min 2.0 2.4 1.4 1.7 1.9 2.1 Apyral 40CD allows highly filled compounds having good melt flow properties showing good flame retardancy, especially when combined with fine boehmite filler (Apyral AOH 180) LOI = 48,2 %O 2 PHRR = 173 kw/m 2 TTI = 80 sec Heat flux = 50 kw/m 2 Horizontal orientation Specimens cut out of compression moulded plates
Conclusions Apyral 40CD is a new non post treated fine precipitated ATH quality, offering good conveyance properties without any loss on bulk density good flow, discharge and feeding properties low dust emissions during powder handling (discharge etc.) good filler uptake and dispersion (low power uptake, low torque) - lower compound process costs (high throughput in continuous lines, low batch times in case of internal mixers) good mechanical and flame retardancy properties and outstanding low melt viscosity of standard LSFOH compounds high extrusion speeds of standard LSFOH compounds - lower extrusion costs an option for processable, highly filled and flame retardant LSFOH compounds - especially when combined with other fillers