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Advances in Wire and Cable Flame Retardant Compounds - Low Smoke Halogen Free by Krishna Joshi# and Sushil Kumar Rajan§ , Duraline India Pvt. Limited, Mexichem Specialty Compounds Business, India
Presented by:
§Sushil
Kumar Rajan, T., Ph.D.,
VP – Appl. Dev and Eng / Tech, AMEA Region Duraline India Pvt. Ltd., Mexichem Specialty Compounds
Advances in Wire and Cable Flame Retardant Compounds – Agenda This presentation does not go into the details of Technology but offers a broad flavour of examples, emerging standards & trends. It is divided into the following segments:•
Background of Mexichem®
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Low Smoke Halogen Free – Context and drivers
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Technology & Applications
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Current Progress and Trends
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Emerging Standards – UL and CPR in particular
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Summary
Background of Mexichem® and Specialty Compounds Business
About Mexichem Mexichem is a leading provider of products and solutions across multiple sectors from petrochemical to construction, infrastructure, agriculture, healthcare, transportation, telecom and energy, among others.
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Commercial activities in more than 100 countries Operations in more than 30 countries Over 18,000 employees >120 production plants 2 fluorite mines 8 training academies 16 R&D laboratories >71,000 points of sale
Compounds Business – all polymers ! Mexichem’s Compounds Business specializes in the design and development of Fire Retardant PVC, PVC, Low Smoke Zero Halogen, Thermoplastic Elastomer and Olefin compounds as well as a range of color concentrates for a wide rage of applications across these markets.
Markets we serve: Footwear
Product Portfolio
Specialty Compounds: Garaflex®
Smokeguard®
TPU
TPE, TPO, TPV
PLENUM
Specialty Compounds
Specialty Compounds
Specialty Compounds
Specialty Compounds
Evoprene®
Alphaseal®
Micraflo®
Vinastab
TPE
PVC, TPE
Specialty Compounds
Specialty Compounds
Specialty Compounds
Specialty Compounds
Megolon®
Garathane®
LSHF
Setting the context
Why Halogen free? • Historically, since the 1970s, European safety standards of cable design have focused on cable designs that exclude halogens in the composition, while the US Standards have focused on the product’s fire resistance properties and its resistance to propagation of flame during fire conditions. • With added impetus from the CPR – enforced EU Regulations (since July 2017) to include permanently installed cables under construction materials. • As a general rule, US Standards have been more emphatic on the wet electrical properties of wires and cables. • Wire and cable insulations can be divided into two distinct types thermoplastic and thermoset. • A thermoplastic material will melt when exposed to high temperatures while a thermoset material will generally not melt; Of Course, both could be designed to form a char that would resist fire propagation. • Flame retardant chemistry, of the early 20th century, began with the broad utilization of halogenated flame retardants. Halogens (Group VII or 17 of the Periodic Table). Subsequently, it has extended to deploy other elements too. • The US Standards applicable to the industrial market addressing smoke generation are UL 44 and UL 1685, while ICEA T-33-655 and MILDTL- 24643 address halogen content measurements.
Harmonization of Standards - Drivers Europe was the first to introduce LSHF technology
Conformité Underwriter’s Européenne Laboratory
– also called LS0H, LSZH, or LHNH in literature • European Union (EU) specifications and requirements EU approach to cable standards being adopted elsewhere • China / Asia • Brazil • USA Cable producers need to meet several flame tests: UL, EN, CSA, and IEC • One cable design that can be sold globally Global companies consolidating product portfolio • LSHF compounds often provide the necessary solution
Low Smoke Halogen Free - Drivers Today, LSHF compounds are used world-wide In certain applications, LSHF has almost completely replaced PVC • For example, data cables in Europe Specifications are strongly influenced by IEC or European experience The LSHF market is expected to continue to grow • Halogenated flame retardants under environmental pressure
Ongoing LSHF compound development considers global standards and specifications for a variety of applications while addressing environmental concerns.
Benefits of LSHF Compounds
Formation of dense smoke and/or toxic fumes Cables containing halogens measure high toxicity Must allow people time to escape fire Transit rail, ships, hospitals, high-rise, airports
Formation of acidic fumes Cables containing halogen measure high acidity Damage to sensitive and strategic electronics Power stations, computer suites, radar, ships
LSHF Compounds are formulated for low toxicity and low corrosivity.
LSHF Solutions in Wire & Cable •
MEGOLON® LSHF compounds introduced in 1982 Originally produced under Scapa branding AlphaGary purchased MEGOLON® from Scapa in 2006 Mexichem® purchased AlphaGary in 2011.
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The Combined Organization offers over 30 years of formulation and manufacturing expertise
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Decades of experience providing solutions to answer today’s specifications European Union requirements Mechanical properties Processing capabilities
Flame Retardant Compounds – Technology and Applications
Polymer Flammability Sequence of steps VAPOR PHASE
CONDENSED PHASE
THERMAL DECOMPOSITION
SOLID POLYMER
ENERGY TRANSFER
MELTING, FLOWING
ZONE OF DIFFUSION ZONE OF POLYMER PYROLYSIS
FLAME FRONT
DIRECTION OF FEED OF FIRE
Ref: Stevens, M.P.; Polymer Chemistry: An Introduction, 2nd ed. Oxford, NY; Oxford University Press 1990. p 126
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Solid polymer melts under heat, flows, and then decomposes to flammable gases. •
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Some thermosets or crosslinked materials do not melt, and decomposition products may be directly pyrolyzed.
Gases with oxygen and combust generating heat and radiant energy. Radiant energy transfers back to condensed phase which sustains combustion of the polymer. It is the polymer structure that dictates flammability
Flammability Measurements Flame Inhibition THE CONE CALORIMETER • •
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A Cone Calorimeter measures the flammability of a material under a constant external heat flux. The flammability is measured by the heat release rate (HRR). As HRR increases, flame spread and flashover increase. PVC has the lowest HRR, due to release of HCl during combustion. PC has the next lowest HRR due to its polymer structure (release of CO2 ) HIPS highest HRR due to chemical structure (hydrocarbon burning).
Flame Inhibition To reduce polymer flammability 3 methods are used, (1) Inhibiting combustion at flame front. (2) Removing heat from polymer. (3) Preventing polymer decomposition / fuel release.
Time in sec
LSHF Compound Technology The Periodic Table – Choice of Flame Retardant Elements* EXCLUDE HALOGENS
FIRE RETARDANCY - PHASE AND MECHANISM VAPOR PHASE DILUTION / RADICAL QUENCH ENDOTHERMIC HEAT ABSTRACTION CONDENSED PHASE INSULATION / INTUMESCENT
*Referenced from: Non-Halogenated Flame Retardant Handbook, Ch:9 “Other Non-Halogenated Flame Retardant Chemistries and Future Flame Retardant Solutions” by Alexander B. Morgan, Paul A. Cusack, and Charles A. Wilkie - for illustration.
LSHF Compound Technology Some Examples - Choice of Flame Retardant Inorganic compounds$
$DSC
EXO
of a mixture of ATH & MDH
Aluminum Trihydroxide {ATH = Al(OH)3} • Lower cost • Endothermic decomposition begins ~ 190oC • Absorbs heat, gives off water, 34% w/w • Requires low compression ratio extruder screw • Limited process window (low decomposition) Al(OH)3 Upto 220oC
ENDO
$DSC
Magnesium Dihydroxide {MDH = Mg(OH)2} • Endothermic decomposition begins • ~ 332oC • Absorbs heat, gives off water, 31% w/w • Wider processing window • Higher shear during processing
Mg(OH)2 Upto 300oC
plot Abstracted from: Method development in thermal analysis. Part 2: by Dr. Markus Schubnell, “Information for users of METTLER TOLEDO thermal analysis systems,” 2/2005, - for illustration.
2Al(OH)3 Al2O3 + 3H2O Mg(OH)2 MgO + H2O
(1) (2)
Hydrated metal hydroxide such as aluminium hydroxide (alumina trihydrate, ATH), and magnesium hydroxide (magnesia dehydrate, MDH) eliminate water during decomposition under heating. The loss of water is endothermic and requires between 1172 and 1373 J/g depending on the source of ATH / MDH, respectively. The temperature ranges are different.
Typical Applications for LSHF Compounds Power, Energy Cables Data, Telecom Cables Circuit Integrity, Fire Survival Cables
Specialty Cables Thermal stress crack resistant High flexibility
Typical Applications for LSHF Compounds
LSHF Compounds for Power, Energy Cables Insulation, Sheathing, Bedding Limited Oxygen Index up to 60% Processing speeds important Must survive harsh environments
LSHF Compounds for Data, Telecom Cables Jacketing / Sheathing, Tight Buffer, Microducts Limited Oxygen Index up to 60% High processing speeds, low die drool Operating temperature up to 105oC
Typical Applications for LSHF Compounds
LSHF Compounds for Circuit Integrity, Fire Survival Jacketing / Sheathing Test includes "shock" and water spray Strong char to protect insulation
LSHF Compounds for Specialty Cables • • •
Thermal Stress Crack Resistance (TSCR) High Tensile and High Flame Retardancy. While the operating temperature is stated to be 90oC as a precaution this is because of difference in test methods.
In the Europe hot pressing is used as a defining criterion for maximum operating temperature, while in the USA in accordance with UL, an ageing test is performed to determine the same parameter, and this and could be specified as 125°C, which means that the results are good even after ageing at 150°C
LSHF – Current market trends
Current Trends Compound development must answer marketplace trends POWER CABLES • Traditionally SWA (Steel Wire Armored) • Harsh environments > 40oC • BS regulations • Hot pressure test @ 90oC Thermal Crack Resistance (TSCR) Testing at Various Temperatures
• Thermal Crack Resistance
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Achieved 90oC with 40% LOI
Current Trends Compound development must answer marketplace trends CIRCUIT INTEGRITY FIRE SURVIVAL CABLES • Fire test: “shock” and spray • Char formation key • Jacket must protect insulation to prevent circuit loss •
Two-hour fire test. Passing this test requires strong char integrity.
§ Where
§LTS
compliance under BS7655
LTS refers to requirements for thermoplastic sheathing compounds under BS7655 and range from 1-4.
Current Trends Compound development must answer marketplace trends HIGH TENSILE STRENGTH & HIGH FLAME RETARDANCY
• Low Brittle Point • Use grafted Compounds • UL temperature rating 125oC • Determined by an ageing method specified by UL.
Current Trends Compound development must answer marketplace trends
FLEXIBITY SIMILAR TO PVC • Jacket and Insulation applications • Lower specific gravity • Intumescent char technology • Excellent fire performance • Of Course, the cost would be higher.
LSHF – Emerging Standards
Underwriters Laboratories LSHF Listing
• UL Certified Compounds: Halogen Free • Gives cable producers confidence that compounds are monitored by UL • Makes product selection easier • Requests for “-HF” listings continue to grow
CPR Classification of Cables under EU •
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CPR is short for the Construction Products Regulation (EU 305/2011), which is part of the European Union legislative framework supporting free movement of goods across the borders in the EU region. CPR identifies a number of basic requirements that shall be met by products used in construction works (e.g. buildings, but also roads, bridges, etc.), some of which are “mechanical resistance and stability” (to avoid collapse etc.), “safety in case of fire” (impact on spread of fire, smoke generation, etc.), and “hygiene, health and the environment” (emission of dangerous substances, toxic gases, etc.). The basic reference standard for cables and their performance with respect to fire under the CPR is: EN 50575:2014 (incl. A1:2016) Power, control and communication cables – Cables for general applications in construction works subject to reaction to fire requirements. EN 50399 is a test method for bunched cables under fire conditions, similar, but not identical, to the IEC 60332-3-series. It has additional requirements for testing of heat release and smoke production during the test.
EN50399 CPR fire test classes – an overview
Decreasing contribution to fuel a fire
7
Smoke emission 5 Classes Minimum Contribution to Fire
Little Smoke production and slow smoke propagation.
Burning Droplets 3 Classes
Smoke Acidity 3 Classes
No burning droplets or particulate
Tr > 80%
Average
Increasing Contribution to Fire
Tr ≥ 60% 4.3 a2 µ < 10 µS/mm and pH > 4.3
Undetermined contribution
EN50399 CPR fire test classes - Example
Some statistics • World Polymer demand 322 M Mt • Indian Polymer demand 15 M Mt • Indian Polymer usage is 11 kg per capita – world average is 28 kg, China is 38 kg, Brazil 32 kg, Europe 68 kg and USA 109 kg • Usage of polymers in W&Cs is about 5.9% • In India, with the same spread, it would be about 0.8 M Mt
Summary Europe has led the trend toward Low Smoke Halogen Free technology. Cable producers are seeking global solutions. LSHF technology is appropriate for a variety of cable requirements • The property offerings continue to expand LSHF development must answer current market trends • Technology continues to expand Mexichem® with its decades of expertise in polymers and compounding would offer its customers, “state of art” solutions in the W&Cs, and more specifically, the LSHF, space.
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Safety of people and of communication infrastructure during a fire continues to be the highest priority while we also address environmental concerns.
Thank you for your time Questions?
Some statistics – back up • World Polymer demand 322 M Mt • Indian Polymer demand 15 M Mt • Indian Polymer usage is 11 kg per capita – world average is 28 kg, China is 38 kg, Brazil 32 kg, Europe 68 kg and USA 109 kg • Usage of polymers in W&Cs is about 5.9% • In India, with the same spread, it would be about 0.8 M Mt
