ADDITIVES | FLAME RETARDANTS
the solid and gas phase of a fire, are said to work best with all types of phosphorus-based derivatives, and also in intumescent systems for coatings and plastics (polypropylene for example), where Le Gal says the effect is quite strong. They are effective at loadings as low as 0.5-2.0%. Their fine particle size gives them “excellent” dispersibility, it is claimed. “The flame retardant loading is almost always
associated with major drawbacks when it comes to mechanical properties or electrical properties, as well as adding a substantial formulation cost,” says Le Gal. “We see a clear differentiating edge over other synergists.” Paxymer continues to market its functional
Above:
Halogen-free flame retardant systems are gaining ground in electrical applications
NY, claims to be the leading producer of halloysite clay and advanced natural iron oxide solutions from its Dragon Mine property in Eureka, in Utah in the US (which is the largest commercial source of halloysite in the western hemisphere). The com- pany’s Dragonite halloysite clay products are described as multifunctional additives that not only act as a synergist with different flame-retardant systems but also provide other features such as enhanced nucleation (especially in polyethylene) and an increase in tensile and flexural strength without compromising impact strength. In films, they can also cause a significant decrease in thermal conductivity as well as improved barrier to gases, scavenging of ethylene gases and the controlled release of antimicrobials. Dragonite is loaded at a rate typically between 1-3 wt% in the final polymer formulation. The choice of grade is based upon whether the polymer is susceptible to degradation by acidic surface hydroxyl groups in the clay.
Halogen-free gains Songwon is targeting halogen-free flame retard- ants with its new Songflame organic synergists for plastics and coatings. They are based on a platform technology that the company began working on around three years ago. It is looking at applications in electrical and electronics and says that during the development phase it has received a positive response from the market. “We are pushing the boundaries and giving
more possibilities for halogen free flame-retardant materials,” says André Le Gal, Leader, Market Center Flame Retardants. “We are working on obtaining improved cost efficiencies, and we are also going for higher performance. We have a building block that is quite broad in terms of application potential.” The new synergists, which are effective in both
32 COMPOUNDING WORLD | December 2019
polymer-based synergist for halogen-free flame retardants. The company has previously had success in reducing the amount of one such product, Adeka FP2500, while maintaining V-0 properties. “A number of phosphorus/nitrogen chemistries are currently being evaluated,” says Managing Director Amit Paul. “Paxymer can typically reduce the P/N additive content by 4-8% with an addition of the organic synergist between 0.5-2.0%. The technology works well in polyolefins. The synergist has also shown promise in glass and natural fibre filled polymers.” The company is currently working on filled PP grades with talc and CaCO3
. “It is a significant
challenge to achieve V-0 with halogen-free solutions [in such compounds],” he says. The company says it is also developing novel analytical techniques for gas-phase characterisa- tion of FR additives. “The market needs to be able to find and optimise competitive, functional and efficient formulations quickly,” says Paul. “This is particularly useful when involved in costly large- scale testing such as the EN13501. The analytical tool-kit enables comparison of efficiency between different chemistries and formulations with the aim of providing a better starting point for formulation. This reduces the need for large Designs of Experi- ments and allows for more precise optimisation and faster deployment of formulations.” The Paxymer technology works by providing
char reinforcement. It propagates cross linking at fire temperatures and acts as a non-dripping additive as a replacement for commonly used fluoropolymers. It also reduces and delays the peak heat release rate.
Liquid synergists Momentive recently introduced SFR 100 silicone fluid, a new liquid synergist that can be used in various polymers, including polypropylene, polyethyl- ene, polycarbonate and other thermoplastics. It is a
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IMAGE: SHUTTERSTOCK
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