applications feature | Wire and cable compounds
offshore platforms and ships, time to evacuation is a real challenge and makes fi re safety all the more critical. New cable jacketing compounds in Teknor Apex’s
Flexalloy range based on high-molecular-weight PVC withstand harsh industrial environments such as those in mining and oil drilling. Teknor Apex says the compounds provide the elasticity and low-temperature toughness of thermoplastic elastomers, with PVC benefi ts like fl ame retardancy. There are two grades, Flexalloy 9616-94 and Flexalloy 9617-79. The fi rst is a high-hardness elastomer that the
producer says provides crush and impact resistance and UV stability for uses like mining cable, and fl ame retardance for applications such as industrial Ethernet networks. The compound has a Shore C hardness rating of 73, equivalent to 94 on the Shore A scale, with a maximum continuous operating temperature of 75°C. It can be used at temperatures as low as -40 °C. Limiting oxygen index (LOI) is 38%. Flexalloy 9617-79, aimed at applications in oil drilling and chemical environments, contains a specialty plasticizer that helps provide high resistance to oils and chemicals. The 79 Shore A compound has a maximum continuous operating temperature rating of 105°C and an LOI of 35%. Mike Patel, director of marketing and business
development for the Vinyl Division of Teknor Apex, says that Flexalloy products provide exceptional ruggedness and durability yet are more cost-effective than TPEs. Lubrizol offers a further alternate solution for
down-hole applications. At the Polymers in Cables 2014 conference organized by Compounding World publisher AMI in Philadelphia, applications engineer Chetan Makadia discussed various types of high-temperature thermoplastic polyurethanes (TPUs) for jacketing, including a new high temperature TPU-C. Makadia said that there is a misconception in the
cable industry that TPUs are only good for applications with temperatures up to 80°C; this is because under Section 50 of the relevant UL standard, 1581, TPUs
Typical properties of Teknor Apex’s Flexalloy 9617-79 PVC cable compound
Property
Hardness (Shore ‘A’ Duro +/-3), 15 Second Reading 79 Density, g/cm3
Tensile Strength, MPa Elongation, % Brittle Point, °C
Limiting Oxygen Index, %
Maximum Continuous Operating Temp., °C Oil Rating
24 COMPOUNDING WORLD | May 2015
Value ASTM standard D-2240 D-792 D-638 D-638 D-746
1.36
12.72 430 -38
35.5 105
D-2863 4 Days @ 100°C UL-1277
could only be rated 80°C via short-term aging, and there was no TPU-specifi c short-term aging criteria for higher ratings (TPUs age differently from other fl exible polymers around which the standard is written, since they contain no plasticizers or oils). However, Lubrizol submitted new proposals for
testing TPUs under UL 1581. It has “standard” TPUs that are rated at either 90°C or 105°C under the new requirements (see table), and it has a new type that performs even better. It is stronger, has particularly good resistance to abrasion and chemicals, and shows high long-term thermal and hydrolysis resistance.
Flame retardant advances PolyOne recently launched Eccoh XLS low smoke and fume, non-halogen formulations for fl ame retardant wire and cable applications. The company says that with the introduction of moisture-cured Eccoh XLS technol- ogy, wire and cable manufacturers can now choose the most cost-effective technology for specifi c production environments when selecting a low smoke and fume, non-halogen composition: dry silane, e-beam irradia- tion, or moisture cure. “Eccoh XLS enables manufacturers to effi ciently
process a non-halogenated, fl ame-retardant material without capital investment in extra equipment or adding steps to complete crosslinking,” says PolyOne. The new offering was developed for applications including low-voltage power cables for building and construction use and specialty wire and cable for marine environments. No precise dosing of catalyst is required, no volatile or harmful chemicals are needed, nor investment in E-beaming plant required, and existing sauna or water baths can be used for accelerated curing. Alternatively, reliable ambient curing takes less than 10 days. “One noticeable trend in the wire and cable industry
is the increasing use of treated ground calcium carbonates in wire insulation compounds which historically have used non-surface-treated calcium carbonates,” says Huber Engineered Materials, which produces various halogen-free fi re retardant additives and ground calcium carbonate grades. “The addition of treated ground calcium carbonate
results in a dramatic increase in linear output and smoother surface fi nishes, due to the increased lubricity spread over the high surface area of the particles,” says the company. “In addition, cold weather physical properties are often improved for those applications requiring it. Plasticizer levels can often be optimized for even greater cost savings.” Huber offers a variety of Hubercarb calcium carbonate in two- and three-micron grades, as well as high-purity Optifi l one-micron grades for wire jacketing and insulation.
www.compoundingworld.com
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