Non-Hazardous Flame Retardant Synergists for Polymers

Robert Leeuwendal

Chemspec 2018, Cologne

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40 countries

Polymer Structure and Flammability

Char formation- model and mechanism

Role of synergists in flame retardant systems

Examples of Flamtard synergist solutions

Conclusions

Content

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40 countries

Polymer Structure

Polyethylene 17 Polypropylene 17 Polymethylmethacrylate 17

Polystyrene 18

Polyvinylchloride 45

Polytetrafluoroethylene 95

and influence on flammability (LOI)

Polycarbonate 26

Polyetheretherketone 38

Polyphenylenesulfide 44

n

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Polymer FR Additives general principles

~Br, ~Cl+

Sb2O3

Al (OH)3

Mg(OH)2

Phosphatebased

Increasing regulatory pressure on chemicals management and performance requirements (i.e. SBI, smoke) cause established flame retardant solutions to be abandoned or adapted to meet new criteria

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Char Formation

Di Blasi and Branca, 2001

Melting / Softening

Intra-molecular X-ing

Pyrolysis

Oxidative Combustion

T

mechanism and model

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Char Formation intumescent system

Intumescent Protective Coating (aquaeous)

Solution Water (30w%)

Binder EVA Copol (14w%)

Acidic Source Ammonium polyphosphate (25w%)

Carbon Source Penta ehrytritol (15w%)

Spumific or blowing agent Melamine (16w%)

Ratio and concentration of additives determines:

Expansion factor

Number of foam cells

Strength of foam

Percentage charring

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Degradation Model

Di Blasi and Branca, 2001

Problem with Polymer Char:Keeps burning or smoldering if mass and heat transfer are not eliminated

Approach: Build improved char structures and charring mechanisms

How: Use of synergists

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Flamtard Synergists for PVC and halogenfree flame retardant systems

Synergist Flamtard H Flamtard S Flamtard V

Chemical nature Zinc tin oxide Zinc tin oxide Metal doped silicate

Function Promotes X-linking Promotes X-linking High temperature flux

Particle size 1-2 micron 1-2 micron 4-6 micron

Polymer processing < 2200C > 2200C………. > 2200C………..

Benefits in PVCLow smoke, (partially) replaces Sb2O3

Low smoke, (partially) replaces Sb2O3

Partially replaces Sb2O3

Benefits in HFFR materialsImproved char strength and consistency with P flame retardants

Improved char strength and consistency with P flame retardants

Improved char strength and consistency

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Polyurethane Foam

Component (phr) PUR PUR/AAP PUR/ZHS PUR/AAP/ZHS

PU Silpak 200 A + B 100 85 95 80

Alkyl aryl phosphate/phosphonate 15 15

Zinc hydroxy stannate 5 5

Cone Calorimeter @ 35 k/m2

Peak rate of Heat Release (kW/m2) 1079 834 1033 619

Time of Peak RHR (s) 75 76 85 81

Avg heat Release Rate (kW/m2) 349 327 373 294

Total Heat Released (MJ/m2/g) 58.8 49.3 62.1 47.7

Avg Mass Loss Rate (g/m2s) 21.4 21.8 22.8 16.6

Mass Residue (w%) 7.7 5.9 4.5 9.7

Feng Yang, Gordon Nelson, Florida Institute of Technology, Melbourne, FL 32901

synergism with zinc hydroxy stannate

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Polyurethane Foam char analysis after cone calorimeter burning

Feng Yang, Gordon Nelson, Florida Institute of Technology, Melbourne, FL 32901

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40 countries

Polyamide Engineering Plastic

Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103

synergism with zinc stannate

Component (phr) 1 2 3 4 5 6 7 8 9

PA6T/66 (Vestamid HT) 55 55 55 55 55 55 55 55 55

Glass fiber ( 30 30 30 30 30 30 30 30 30

Alumina di-ethyl phosphinate 7.5 0 15 0 0 7.5 15 11.25 3.75

Zinc stannate 7.5 15 0 15 15 7.5 0 3.75 11.25

Polymer formulations were evaluated on flame retardant properties by UL94VB, 0.8 mm and in tested for rate of heat release, smoke formation in the Cone Calorimeter.

Burned test specimen were analysed for char content and morphology.

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Polyamide Engineering Plastic

Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103

synergism with zinc stannate

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40 countries

Polyamide Engineering Plastic

Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103

synergism with zinc stannate

PA6T/66 Flamtard S(85/15)

PA6T/66 AliP Flamtard S(85/7.5/7.5)

PA6T/66 AliP Flamtard S(85/15/0)

Test Specimen Residues after Cone Calorimeter Experiment 50kW/m2 heat flux

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Polyamide Engineering Plastic

Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103

synergism with zinc stannate

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40 countries

Examples Silicon Elastomer synergism with low melting glass

Mechanical strength of chars after burning silicon polymer – mica compounds

Investigation of the ceramifying process of modified silicone silicate compositions, Mansouri, Burford, J. Mater. Sci., Aug 2007

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Conclusions

Flamtard synergists are used at low loadings to improve:

a. Char formation in PVC and phosphate based FR polymer materials, leading to lower smoke and rate of heat release (Flamtard H, S)

b. Barrier properties of char by filling micro cracks, voids, and andbuild viscosity in the decomposition zone, leading to improved flame retardant mechanisms (Flamtard V)