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additives | Flame retardants


Clariant uses different synergists in its various Exolit OP grades to improve performance.


Source: Clariant


Dalmau, director of the company’s Special Additives business unit, says these products offer versatility in terms of the temperatures and shear rates that can be used during processing. He says this distinguishes them from other nanoclays that have been on the market for some time now. Traditional bentonite and montmorillonite nanoclays


have very high charge densities that require a high amount of quaternary ammonium for exfoliation of the platelets, which limits processing temperatures, and the bonds are ionic. But the Tolsa clays, which have a more needle-like structure, have low charge density. There is no need for any cationic exchange involved in the exfoliation and the bonds are covalent, so are more stable. Modification with silanes enables them to be used in a wider range of polymer matrices with higher processing temperatures. Adins Clay can be combined at addition rates of 2-3% as a char promotor with mineral flame retardants such as aluminium trihydrate (ATH) or magnesium hydroxide (MDH) and intumescents like ammonium polyphos- phate.


Adins Fireproof is aimed at special wire and cable


applications. This is also based on sepiolite but is doped with different phosphate species to create a low melting temperature glass char under fire conditions. It can be used in polyolefins and EVAs as well as some rubbers. Dalmau says Tolsa’s next move will be to expand into


additives for more polymers, including polyamides and PVC. In PVC, for example, it should be possible to replace as much as 50% of ATO in wire and cable compounds for applications in trains and in construc- tion, which will help in qualification for the EU Con- struction Products Regulations (CPR). Tolsa says its flexible technology facilitates modifica- tion of the sepiolite clay to meet individual customer requirements in terms of heat and smoke performance. Applications include railway and transportation seating


22 COMPOUNDING WORLD | December 2016


and flooring as well as structural parts and low, medium and high-voltage cables. Adins additives are sold as a powder or can be supplied in other physical formats. BYK’s Cloisite nano clay-based synergists are


intended for use in combination with ATH and MDH. The company has recently developed a new grade, RXG 7581, which is a further development of its existing Cloisite-20 product that offers improved efficiency to help reduce the percentage of inorganic FR required. It is available for sampling now and is particularly intended for polyolefin cables. In July, BYK acquired Dutch additives specialist


Addcomp, giving it (among other things) an additional range of halogen-free flame retardant masterbatches. Jochen Wilms, Manager for Thermoplastics Applica- tions for Additives at BYK, highlights solutions for thin applications in polyolefins, including films, with products such as Add-Vance FR 583; such use also enhances UV stability. “BYK is now a leader in additive solutions, with its own technologies to achieve very good dispersion and improved efficiency of the addi- tives, “ Wilms says.


Hybrid alternatives Polymer Dynamix is another company now offering a flame retardant synergist. Dynasil FR is a multi-func- tional silicone-based technology. Marketing Director Viggy Mehta describes it as a hybrid polymer particle that is solid at room temperature and liquefies only under shear or when the host polymer burns. Heat alone will not liquefy it. Mehta says the product improves the efficacy of phosphorus-based flame retardants and also metal hydrates, creating a different type of ceramification that leads to better retardant properties. “The phosphorus reacts in a unique way to form a ceramic coating,” he says. “In a fire, Dynasil unzips and becomes liquid, and then


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