FLAME RETARDANTS
In addition to APP , charring agents , notably polyols or carbohydrates , and a blowing agent to support foam formation , melamine derivates like MC are typically used . New developments in intumescent FRs use coated APPs , which have a lower solubility in water and therefore show a higher stability against hydrolysis . The thermal stability of APP can also be increased by applying a coating allowing for easier processing . Using novel synergists , the performance of intumescent FRs was improved significantly . Table 1 compares an intumescent system with an uncoated APP containing the first generation of synergists and coated APP containing the second generation of synergists . High FR loadings decrease the mechanical properties of the polymeric materials . Thus , in addition to cost reasons , lower FR loadings are preferred . Budenheim ’ s Budit * 669S has a special surface treatment leading to an improved dispersibility in the polymer matrix . Good dispersion of the intumescent system increases FR performance . Furthermore , the mechanical properties are less affected . Budit
i 100 ° c
Polymer ( PE/PP )
669S showed 15 % higher values in tensile modulus and tensile strength in comparison to Budit 667 . Elongation at break values even increased by over 25 %. The mechanical properties of polymer compounds can be improved by using fillers . Intumescent systems work well with neutral talc or in glass fibre-reinforced compounds . In these cases , the FR loading depends also on the amount of filler used . In a recent study , we found that 20 % Budit 669S is sufficient to achieve a V-0 classification in the UL-94 burning test in a PP compound containing 40 % talc , whereas an unfilled compound requires 25 % Budit 669S . Figure 3 shows a specimen containing the coated Budit 669S in comparison with an uncoated system after a migration test . In this test , the specimens are stored for one week at 85 ° C and 85 % relative humidity to evaluate the leaching of ingredients . The coating significantly improves the performance of the intumescent system in the migration test and less blooming was observed . This makes Budit 669S suitable for applications with high humidity .
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2 - Intumescence for protection of polymers
Intumescent FR systems and other non-halogenated FRs ( NHFRs ) have no negative impact on smoke emission or smoke toxicity . This was shown in a comprehensive study conducted by French testing laboratory CREPIM and the Phosphorus , Inorganic & Nitrogen Flame Retardants Association ( PINFA ). 3 The neat polymer mainly contributes to the toxicity and amount of the smoke . In comparison with halogenated FRs , the smoke density and smoke toxicity of NHFRs are lower .
Sustainability of FRs
The EU is pushing several regulations to protect consumers , focusing on the sustainability of chemical products . Changes in the classification of melamine will probably influence the labelling of melamine-containing FRs . The benefits of FRs , i . e . saving lives , are obvious , albeit that new solutions with an improved eco-toxicological profile are required in terms of achieving the ambitious sustainability goals imposed by authorities . NHFRs are seen as more sustainable than traditional brominated systems , which enable the Circular Economy and thus resource efficiency . A revision of the EU ’ s Restriction of Hazardous Substances Directive is expected to further restrict the use of halogenated FRs . In addition , the Ecodesign Directive prohibits the use non-halogenated FRs in the enclosure and stand of electronic displays . NHFRs meet the requirements of the European Green Deal . In addition to the organic growth of the polymer and FR markets , stricter fire safety requirements associated with higher targets for environmental and health protection are leading to growing demand for innovative NHFRs . Plastic waste in the environment is under intense discussions , with the mass media portraying it as one of the biggest environmental problems . Recycling plays an important role in this fight . Different recycling technologies are needed to overcome the waste problem and intensive development is going on .
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