1 Synergies of Metal Molybdates and Metal Hydroxides in Fire Retardant Polyolefin Compounds Alex Isarov, David Temples, Mark Herndon, Tong Chen J.M. Huber Corporation Fairmount, GA 30139 USA 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 2 Background Information J.M. Huber Corporation acquired the Kemgard® product line from The Sherwin Williams Company in August 2010. Kemgard materials are smoke suppressants and char formers based on molybdenum and phosphorous chemistries. Currently, the main application for Kemgard products is in PVC formulations (rigid, flexible, plastisols). Huber is investigating Kemgard performance benefits in other polymer systems including polyolefin-based formulations. Objective – review available data related to FR performance of metal molybdates as fire retardants/char formers in polyolefin based formulations. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 3 Presentation Outline Review of Kemgard technology – precipitation of active phase on the surface of particulate core. Example – zinc molybdate/zinc borate complex. Molybdates as char formers in thermoplastic EVA. Molybdates as char formers in EVA/LDPE blends (thermoplastic and peroxide cross linked). Zinc phosphate/zinc oxide complex as char former in peroxide cross linked EVA/LDPE blends. Conclusions. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 4 Kemgard® Engineered Molybdates Precipitation of molybdates (Ca, Zn) onto the surface of a ppgyarticulate core significantly increases the active surface area of the molybdate phase resulting in enhanced FR efficacy. Inert core: Calcium Carbonate core – Kemgard 911A Talc core – Kemgard 911C, Kemgard 1100 Zinc Oxide core – Kemgard 911B FR-active core Magnesium Hydroxide core – Kemgard MZM, Kemgard HPSS. Zinc Borate core – Kemgard 700Z 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 5 Example - Zn Molybdate /Zn Borate Complex Material Description Sample ID BET surface area ((),measured), m2/gg Zinc borate (core) Zinc borate 2.9 10% zinc molybdate/zinc borate ZMZB-10 5.5 17.4 % zinc molybdate/zinc borate ZMZB-17 5.3 24.8% zinc molybdate/zinc borate ZMZB-24 6.3 Precipitation of Zn molybdate on the surface of Zn borate leads to a significant increase of BET specific surface area A. Isarov et. al. Proceedings of 60th IWCS, 2011, 250-256 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 6 Example - Zn Molybdate /Zn Borate Complex Description BET surface Zinc Molybdate area specific surface (measured), area (calculated), m2/g m2/g Zinc borate 2.9 n/a (core) 10% zinc 5.5 28 molybdate 17.4 % zinc 5.3 16.3 molybdate 24.8% zinc 6.3 16.3 molybdate Higher surface area of zinc molybdate-zinc borate complex is due to high surface area of Zinc molybdate particle on zinc molybdate particles on zinc borate surface. the surface of zinc borate A. Isarov et. al. Proceedings of 60th IWCS, 2011, 250-256 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 7 Materials used in this study ¾Metal hydroxides: Vertex 100 Vertex 100 SP Zerogen 100 Zerogen 100 SP Chemical Identity Magnesium Magnesium Magnesium Magnesium Hydroxide, Hydroxide, Hydroxide, Hydroxide, synthetic synthetic synthetic synthetic Particle size, microns 1.5 1.5 0.8 0.8 BET Surface Area, m2/g 14 14 5 5 Chemical purity Good Good Excellent Excellent Surface Treatment Untreated Vinyl silane Untreated Vinyl silane ¾Molybdates: •Zn molybdate •Ca molybdate •Kemgard MZM – zinc molybdate/magnesium hydroxide complex. •Kemgard 700Z – zinc molybdate/zinc borate complex. ¾Kemgard 981 – zinc ppphosphate/zinc oxide com plex. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 8 Test Formulations: Fire Retardant Polyolefin Compounds Compound Ingredients 1. EVA 64% MDH 30% EVA (28% VA, 3 MFR) 6% compatabilizer/additives 2EVA/LDPE2. EVA/LDPE 65% MDH 20.7% EVA (28% VA, 3 MFR) 12.8% LDPE (2.3 MFR) 1.5% additives 3. XL-EVA/LDPE 65% MDH 19.3% EVA (28% VA, 3 MFR) 12.8% LDPE (2.3 MFR) 1. 4% organic peroxide 1.5% additives 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 9 FR Test Methods • Pyrolysis Combustion Flow Calorimeter – Microscale Calorimeter or Micro Combustion Calorimeter – Developed by US FAA – ASTM D7309-07 • Cone Calorimeter – ASTM E1354 (50kW) • Limiting Oxygen Index – ASTM D2863 • UL-94 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 10 Molybdate Promoted Cross-linking in PVC Dehydrochlorination, polyene formation Cl Cl Δ –(CH2CH)n– –(CH2CH)n-x –(CH=CH)x– + xHCl Crosslinking Cl Z -CH=CHCH- + -CH=CH- -CH=CHCHC=CH- + HCl 6+ Z = Lewis Acid (Mo surface) Higher surface area of zinc molybdate is beneficial for efficient char formation Starnes,,,; W. H., Jr.; Ge, X. Macromolecules 2004, 37, 352-359. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 11 Effect of Zinc Molybdate on Char Formation EVA - 64% total FR loading level Rate of Heat Release Specific Extinction Area 300 1000 Vertex 100 900 Vertex 100 V100/Zinc Molybdate 4:1 250 800 V100/Zinc Molybdate 4:1 V100/Zinc Molybdate 1:1.5 V100/Zinc Molybdate 1:1.5 700 200 2 600 /kg 500 150 2 w/m M KK 400 100 300 200 50 100 0 0 0 200 400 600 800 0 200 400 600 800 Time (s) Time (s) Zn Molybdate facilitates char formation in EVA when used in combination with magnesium hydroxide. LOI 37 37 33 Better char formation manifests itself in the reduction UL94 All failed of heat release rate and delay in secondary RHR and smoke peaks. T. Chen et. al. Proceedings of 58th IWCS, 2009, 569-576 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 12 Zinc Molybdate Promoted Cross-linking in EVA Friedel-Crafts Alkylation O C CH3 O Z -CH=CHCH- + -CH=CH- -CH=CHCHC=CH- + CH3COOH 6+ Z = Lewis Acid (Mo surface) Crosslinking mechanism similar to PVC, surface of zinc molybdate (Mo6+) catalyzes FC alkylation reaction. Does Zn play any role? T. Chen et. al. Proceedings of 58th IWCS, 2009, 569-576 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 13 Effect of Ca Molybdate on Char Formation EVA - 64% total FR loading level Rate of Heat Release Specific Extinction Area 400 1200 Vertex 100 Vertex 100 350 V100/Ca Molybdate 4:1 1000 V100/Ca Molybdate 4:1 300 V100/Ca Molybdate 1.5:1 800 V100/Ca Molybdate 1.5:1 2 250 g kk mm / 200 2 600 M Kw/ 150 400 100 200 50 0 0 0 100 200 300 400 500 600 0 100 200 300 400 500 600 Time (s) Time (s) Ca molybdate is not as efficient as Zn molybdate LOI 31 34 37 in char formation in EVA when used in UL94 All failed combination with magnesium hydroxide. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 14 Ca Molyyybdate vs. Zinc Molybdate in EVA EVA - 64% total FR loading level Rate of Heat Release Specific Extinction Area 300 Vertex 100 1200 Vertex 100 V100/Ca Molybdate 4:1 V100/Ca Molybdate 4:1 250 1000 V100/Zn Molybdate 4:1 V100/Zn Molybdate 4:1 200 800 2 150 /kg 600 22 mm 100 m 400 kW/ 50 200 0 0 0 200 400 600 800 0 200 400 600 800 Time, secon ds Time, secon ds Zn molybdate is a more efficient char former in LOI 34 37 37 the rmop last i c EVA as co m par ed to Ca m ol ybdate. UL94 All failed Synergy between zinc and molybdenum in EVA. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 15 Effect of ZnO and MoO3 on Char Formation in EVA EVA - 64% total FR loading level Rate of Heat Release Rate of Smoke Production 350 10 Zerogen 100 SP Zerogen 100 SP 9 300 Z100 SP/ZnO 4:1 Z100 SP/ZnO 4:1 8 Z100 SP/MoO3 4:1 250 Z100 SP/MoO3 4:1 7 6 2 200 m // 5 ss 150 1/ kW 4 3 100 2 50 1 0 0 0 200 400 600 800 0 200 400 600 800 Time, seconds Time, seconds Molybdenum oxide is a much better char former LOI 45 44 42 in thermoplastic EVA as compared to Zinc oxide. UL94 V0 Fail Fail Synergy between zinc and molybdenum in EVA. 23rd Annual BCC Conference: Recent Advances on Flame Retardancy of Polymeric Materials FIRE RETARDANT ADDITIVES May 21-23, 2012 16 Effect of Zn Molybdate/MDH Complex on Char Formation EVA - 66% tota l FR l oadin g l ev el Rate of Heat Release (50 kW) Rate of Smoke Production 250 2.5 Vertex 100/KG MZM 5:1 (66%) Vertex 100/KG MZM 5:1 (66%) Vertex 100 (66%) 200 202.0 Vertex 100 (66%) 1.5 2 150 1/s kW/m 100 1.0 0.5 50 0.0 0 0 200 400 600 800 1000 0 200 400 600 800 1000 Time (s) Time (s) LOI 41 41 Kemgard MZM – Zn molybdate/MDH complex.