Synergies of Metal Molybdates and Metal Hydroxides in Fire … · 2012. 6. 6. · Synergies of...

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Synergies of Metal Molybdates and Metal Hydroxides in Fire Retardant

Polyolefin Compounds

Alex Isarov, David Temples, Mark Herndon, Tong ChenJ.M. Huber Corporation

Fairmount, GA 30139 USA

FIRE RETARDANT ADDITIVES

23rd Annual BCC Conference:Recent Advances on Flame Retardancy of Polymeric Materials

May 21-23, 2012

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Background InformationBackground InformationJ.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 ofObjective – review available data related to FR performance of metal molybdates as fire retardants/char formers in polyolefin based formulations.



May 21-23, 2012

3

Presentation OutlinePresentation OutlineReview 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.



May 21-23, 2012

Kemgard® Engineered Molybdates4

Precipitation of molybdates (Ca, Zn) onto the surface of a particulate core significantly increases the active surface area

Inert core:

p g yof the molybdate phase resulting in enhanced FR efficacy.

Inert core:Calcium Carbonate core – Kemgard 911ATalc core – Kemgard 911C, Kemgard 1100Zinc Oxide core – Kemgard 911B

FR-active coreMagnesium Hydroxide core Kemgard MZM Kemgard HPSSMagnesium Hydroxide core – Kemgard MZM, Kemgard HPSS.Zinc Borate core – Kemgard 700Z



May 21-23, 2012

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Example - Zn Molybdate /Zn Borate Complex

Material Description Sample ID BET surface area (measured), m2/g( ), g

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



May 21-23, 2012

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Example - Zn Molybdate /Zn Borate Complex

Description BET surface area (measured),

Zinc Molybdate specific surface area (calculated),(measured),

m2/garea (calculated), m2/g

Zinc borate (core)

2.9 n/a

10% zinc molybdate

5.5 28

17.4 % zinc molybdate

5.3 16.3

24.8% zinc molybdate

6.3 16.3

Zinc molybdate particle onHigher surface area of zinc molybdate-zinc

Zinc molybdate particle on the surface of zinc borate

borate complex is due to high surface area of zinc molybdate particles on zinc borate surface.

A Isarov et al Proceedings of 60th IWCS 2011 250-256



May 21-23, 2012

A. Isarov et. al. Proceedings of 60 IWCS, 2011, 250-256

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Materials used Materials used in this in this studystudy

Vertex 100 Vertex 100 SP Zerogen 100 Zerogen 100 SP

Metal hydroxides:

Chemical Identity Magnesium Hydroxide, synthetic

Magnesium Hydroxide, 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

Molybdates:•Zn molybdate•Ca molybdate

/•Kemgard MZM – zinc molybdate/magnesium hydroxide complex.•Kemgard 700Z – zinc molybdate/zinc borate complex.

Kemgard 981 – zinc phosphate/zinc oxide complex.



May 21-23, 2012

g p p p

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Test Formulations:Fire Retardant Polyolefin CompoundsFire Retardant Polyolefin Compounds

Compound Ingredients

1. EVA 64% MDH30% EVA (28% VA, 3 MFR)6% compatabilizer/additives

2 EVA/LDPE 65% MDH2. EVA/LDPE 65% MDH20.7% EVA (28% VA, 3 MFR)12.8% LDPE (2.3 MFR)1.5% additives

3. XL-EVA/LDPE 65% MDH19.3% EVA (28% VA, 3 MFR)12.8% LDPE (2.3 MFR)1 4% organic peroxide1.4% organic peroxide1.5% additives



May 21-23, 2012

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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 IndexASTM D2863– ASTM D2863

• UL-94



May 21-23, 2012

Molybdate Promoted Cross-linking in PVC10

Cl ClDehydrochlorination, polyene formation

–(CH2CH)n–Δ –(CH2CH)n-x –(CH=CH)x– + xHCl

Crosslinking

Z

Crosslinking

Cl

-CH=CHCH- + -CH=CH- -CH=CHCHC=CH- + HCl

Z = Lewis Acid (Mo6+surface)

Starnes, W. H., Jr.; Ge, X. Macromolecules 2004, 37, 352-359.

Higher surface area of zinc molybdate is beneficial for efficient char formation



May 21-23, 2012

, , ; , , ,

Effect of Zinc Molybdate on Char Formation11

Rate of Heat Release

300

Specific Extinction Area

1000

EVA - 64% total FR loading level

150

200

250

300

Kw

/m2

Vertex 100V100/Zinc Molybdate 4:1V100/Zinc Molybdate 1:1.5

400500600700800900

1000

M2 /k

g

Vertex 100V100/Zinc Molybdate 4:1V100/Zinc Molybdate 1:1.5

0

50

100

0 200 400 600 800

K

0100200300400

0 200 400 600 800

Time (s)Time (s) Time (s)

Zn Molybdate facilitates char formation in EVA when used in combination with magnesium hydroxide. LOI 37 37 33

UL94 All failedBetter char formation manifests itself in the reduction of heat release rate and delay in secondary RHR and smoke peaks.

T. Chen et. al. Proceedings of 58th IWCS, 2009, 569-576

UL94 All failed



May 21-23, 2012

T. Chen et. al. Proceedings of 58 IWCS, 2009, 569 576

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Zinc Molybdate Promoted Cross-linking in EVAFriedel Crafts AlkylationFriedel-Crafts Alkylation

CH3CO

ZO

CH3CO

-CH=CHCH- + -CH=CH- -CH=CHCHC=CH- + CH3COOHZ

Z = Lewis Acid (Mo6+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



May 21-23, 2012


Effect of Ca Molybdate on Char Formation13

y

Rate of Heat Release Specific Extinction Area


250300350400

m2

Vertex 100V100/Ca Molybdate 4:1V100/Ca Molybdate 1.5:1

800

1000

1200

kg

Vertex 100

V100/Ca Molybdate 4:1

V100/Ca Molybdate 1.5:1

050

100150200

0 100 200 300 400 500 600

Kw

/m

0

200

400

600

0 100 200 300 400 500 600

M2 /k

0 100 200 300 400 500 600Time (s)

0 100 200 300 400 500 600

Time (s)

Ca molybdate is not as efficient as Zn molybdatein char formation in EVA when used in

LOI 31 34 37UL94 All failedin char formation in EVA when used in

combination with magnesium hydroxide. UL94 All failed



May 21-23, 2012

Ca Molybdate vs. Zinc Molybdate in EVA14

y yEVA - 64% total FR loading level

Rate of Heat Release Specific Extinction Area

150

200

250

300

m2

Rate of Heat ReleaseVertex 100V100/Ca Molybdate 4:1V100/Zn Molybdate 4:1

600

800

1000

1200

2 /kg

Specific Extinction AreaVertex 100V100/Ca Molybdate 4:1V100/Zn Molybdate 4:1

0

50

100

0 200 400 600 800

kW/m

Ti d

0

200

400

0 200 400 600 800

m2

Ti d

Zn molybdate is a more efficient char former in thermoplastic EVA as compared to Ca molybdate.

LOI 34 37 37UL94 All failed

Time, seconds Time, seconds

t e op ast c as co pa ed to Ca o ybdate

Synergy between zinc and molybdenum in EVA.

UL94 All failed



May 21-23, 2012

Effect of ZnO and MoO3 on Char Formation in EVA15


350Rate of Heat Release

10Rate of Smoke Production

S

200

250

300

/m2

Zerogen 100 SPZ100 SP/ZnO 4:1Z100 SP/MoO3 4:1

56789

s

Zerogen 100 SP

Z100 SP/ZnO 4:1

Z100 SP/MoO3 4:1

50

100

150kW/

012341

/sMolybdenum oxide is a much better char former LOI 45 44 42

00 200 400 600 800

Time, seconds

00 200 400 600 800

Time, seconds

Molybdenum oxide is a much better char former in thermoplastic EVA as compared to Zinc oxide.

Synergy between zinc and molybdenum in EVA.

LOI 45 44 42 UL94 V0 Fail Fail



May 21-23, 2012

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Effect of Zn Molybdate/MDH Complex on Char FormationEVA - 66% total FR loading level

Rate of Smoke Production

2 0

2.5 Vertex 100/KG MZM 5:1 (66%)

Vertex 100 (66%)

Rate of Heat Release (50 kW)

200

250

Vertex 100/KG MZM 5:1 (66%)

66% tota oad g e e

0.5

1.0

1.5

2.0

1/s

50

100

150

200

kW/m

2

Vertex 100 (66%)

0.00 200 400 600 800 1000

Time (s)

0

50

0 200 400 600 800 1000

Time (s)

Kemgard MZM – Zn molybdate/MDH complex.

Partial replacement of Vertex 100 SP magnesium hydroxide (~ 17%) with

LOI 41 41UL94 V0 V0

Partial replacement of Vertex 100 SP magnesium hydroxide ( 17%) with Kemgard MZM leads to the formation of stronger char, which manifests itself in a delay in appearance of secondary HRR and RSP peaks.

T. Chen et. al. Proceedings of 58th IWCS, 2009, 569-576



May 21-23, 2012


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Zinc Molybdate-Zinc Borate Complex in EVAEVA - 64% total FR loading level6 % tota oad g e e

Partial replacement of Vertex 100 magnesium hydroxide with zinc borate significantly reduces heat release rate and rate of smoke production. LOI 37 37 38

UL94 Fail V0 V0ZMZB-17 is more efficient vs. zinc borate - stronger char manifests itself in an additional delay in the appearance of secondary HRR and RSP peaks.


UL94 Fail V0 V0



May 21-23, 2012

g , ,

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Effect of Zn Molybdate Level on Rate of Heat Release

Increase of Zn


molybdate level leads to longer delay in the appearance of the secondary heat yrelease peak indicating formation of stronger char.

Position of secondary peak of heat release

Zinc Molybdate – Zinc Borate FR synergyA Isarov et al Proceedings of 60th IWCS 2011 250-256



May 21-23, 2012

A. Isarov et. al. Proceedings of 60 IWCS, 2011, 250-256

19

Pyrolysis Combustion Flow CalorimeterZinc Molybdate – Zinc Borate Synergy in Char FormationZinc Molybdate Zinc Borate Synergy in Char Formation

1)Zinc borate does not


1)Zinc borate does not affect PCFC heat release rate;

2)Zinc molybdate delays the second heat release peak;

3)Zinc molybdate –Zinc borate complex reduces total heat

lrelease.

First decomposition step:Evolution of acetic acid

Second decomposition step:Degradation of EVA residue

A I t l P di f 60th IWCS 2011 250 256



May 21-23, 2012


Effect of ZnO and MoO3 on Char Formation20

EVA/LDPE (60/40) blend - total FR loading 65%

Rate of Heat Release Rate of Smoke Production

150

200

250

m2

Rate of Heat Release Zerogen 100 SPZ100 SP/ZnO 4:1Z100 SP/MoO3 4:1

2.0

2.5

3.0Rate of Smoke Production

Zerogen 100 SPZ100 SP/ZnO 4:1Z100 SP/MoO3 4:1

0

50

100kW/m

0.0

0.5

1.0

1.51/s

00 200 400 600 800 1000 1200

Time, seconds

0.00 200 400 600 800 1000 1200

Time, seconds

In thermoplastic EVA/LDPE (60/40) blend, both Zinc oxide and Molybdenum oxide facilitate char formation.

Presence of LDPE increases char forming efficiency of ZnO.

LOI 39 39 37UL94 V0 V0 V0



May 21-23, 2012

Effect of Zn Molybdate on Char Formation21

EVA/LDPE (60/40) blend - total FR loading 65%


150

200

250

m2

Rate of Heat ReleaseZerogen 100 SP

Z100 SP/Zn Molybdate 4:1

1

2.0

2.5

3.0

s

Rate of Smoke ProductionZerogen 100 SP


0

50

100

0 200 400 600 800 1000 1200

kW/

0.0

0.5

1.0

1.5

0 200 400 600 800 1000 1200

1/s

Zn molybdate is as efficient a char former in thermoplastic

0 200 400 600 800 1000 1200Time, seconds

0 200 400 600 800 1000 1200

Time, seconds

EVA/LDPE (60/40) blend as it is in 100% EVA.

This suggests a second char forming mechanism involving Zn and LDPE.

LOI 39 39UL94 V0 V0



May 21-23, 2012

Zn Molybdate vs. Ca Molybdate as Char Formers in Peroxide Cross-linked EVA/LDPE

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XL-EVA/LDPE (60/40) blend - total FR loading 65%


150

200

250

m2

Zerogen 100 SP


Z100 SP/Ca Molybdate 4:12 0

2.5

3.0

3.5Zerogen 100 SP

Z100 SP/Zinc Molybdate 4:1

Z100SP/Ca Molybdate 4:1

50

100kW/m

0.5

1.0

1.5

2.0

1/s

In peroxide cross-linked EVA/LDPE (60/40) blend Zn molybdate is a

00 200 400 600 800 1000

Time, seconds

0.00 200 400 600 800 1000

Time, seconds

In peroxide cross-linked EVA/LDPE (60/40) blend Zn molybdate is a more efficient char former compared to Ca molybdate.

Same trend was observed in thermoplastic EVA and thermoplastic EVA/LDPE blend.

LOI 46 43 41UL94 V0 V0 Fail



May 21-23, 2012

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Zinc Phosphate/Zinc Oxide Complex(Kemgard 981)(Kemgard 981)

Description BET surface area

Zinc phosphate specific surface

(measured), m2/g

parea (calculated), m2/g

Zinc oxide (core)

1.2 n/a(core)30% Zinc phosphate

3.2 7.9

The higher surface area of the Zinc phosphate-Zinc oxide complex is due to the high surface area of Zinc phosphate

Zinc phosphate particles on the surface of Zinc oxide

particles on the Zinc oxide surface.



May 21-23, 2012

Zn Phosphate – Zinc Oxide Complex in Peroxide Cross-linked EVA/LDPE

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EVA/LDPEXL-EVA/LDPE (60/40) blend - total FR loading 65%


150

200

250

m2

Rate of Heat Release

Zerogen 100SP

Z100SP/5% KG 9812.0

2.5

3.0

Rate of Smoke Production

Zerogen 100SP

Z100SP/5% KG 981

0

50

100kW/m

0 0

0.5

1.0

1.5

1/s

00 200 400 600 800 1000 1200

Time, seconds

0.00 200 400 600 800 1000 1200

Time, seconds

Zinc phosphate/zinc oxide complex facilitates char formation in peroxide cross-linked EVA/LDPE blends at lower MDH replacement levels (5%).

Improved char formation was not observed at higher MDH replacement levels.

LOI 44 43UL94 V0 V0



May 21-23, 2012

levels.

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ConclusionsConclusionsZinc molybdate contributes to char formation in EVA formulations by promoting cross-linking during EVA decomposition. Proposed mechanism – Friedel-Crafts alkylation catalyzed by Mo6+.

The FR performance of magnesium hydroxide in EVA can be improved by replacing part of MDH with a Zn molybdate/MDH complex (KemgardMZM) or a Zn molybdate/Zn borate complex (Kemgard 700Z)MZM) or a Zn molybdate/Zn borate complex (Kemgard 700Z).

In formulations containing LDPE (EVA/LDPE blends), Zn2+ ions play an important role in char formation Possible mechanism – polymer cross-important role in char formation. Possible mechanism polymer crosslinking via carboxyl groups formed during thermo-oxidative degradation of polyethylene.

Zn phosphate/ZnO complex (Kemgard 981) facilitates char formation in peroxide cross-linked EVA/LDPE blends at lower MDH replacement levels (5%).



May 21-23, 2012

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Thank you for your attention!Thank you for your attention!

Our contact information:

Alex Isarov, David Temples, Mark HerndonJ.M. Huber Corporation

Fairmount, GA 30139 USA+1-706-337-3243

[email protected]@huber.commark herndon@huber [email protected]



May 21-23, 2012

Synergies of Metal Molybdates and Metal Hydroxides in Fire … · 2012. 6. 6. · Synergies of...

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