FLAME RETARDANTS after multiple extrusions . 1 However , the insufficient performance of Exolit OP 1400 in glow wire ignition temperature ( GWIT ) test ( Figure 1 ), a special test standard for plastic components in household appliances , had been an obstacle to its use in this application .
White goods applications
Safety is very important in the home appliance industry . Due to the possibility of human error , excess current or short circuit failures within an appliance wiring system , flammability standards are in place for materials used within an appliance . Historically , a number of methods were developed to evaluate material flammability and fire resistance . These include direct and indirect flame testing methods . An example of the former is defined in the UL 94 specification . This longaccepted method involves applying a flame directly to a vertically or horizontally mounted specimen under controlled conditions . An indirect flame method features a non-flaming heat source applied to a sample . GWIT testing , which is used within the European appliance industry today , is an example of this method . Test results from applying these methods provide a way to compare tendency of the materials to resist ignition , self-extinguish flames ( in case ignition occurs ) and not propagate fire via dripping . 2 The IEC 60335-1 standard governs the safety of household appliances . Within the specification , GWIT testing is used to evaluate the flammability of non-metallic materials supporting current-carrying connections used within the appliance . Test severity is determined by whether the appliance is attended or unattended during use , and by the amount of current carried by the connection ( Figure 2 ). Attended appliances are those operated by an attending consumer such as vacuum cleaners , irons and coffee machines . Unattended appliances are those that are set in place and operated
Exolit OP 1400 Exolit OP 1480 ( TP )
UL 94 at 0.4 , 0.8 and 1.6 mm V-0 V-0
GWIT at 0.75 mm [° C ] 750 800
GWIT at 1 mm [° C ] 750 800
GWIT at 1.5 mm [° C ] 775 825
GWIT at 3 mm [° C ] 800 825
GWFI [° C ] at 1,5 and at 0.75 mm 960 960
Table 1 – 30 % GF PA 6,6 with 23 % FRs
Exolit OP 1400 Exolit OP 1466 ( TP )
UL 94 at 0.4 , 0.8 and 1.6 mm V-0 V-0
GWIT at 0.75 mm 750 800
GWIT at 1.5 mm 750 800
GWIT at 3 mm 775 825
GWFI at 0.75 mm 960 960
GWFI at 1.5 mm 960 960
Table 2 - 30 % GF PA 6 with 23 % FRs
on their own , such as refrigerators , cooking units , dishwashers , washing machines and dryers . To be used in unattended household appliances and as insulation materials around currents above 0.2 amperes , PAs must pass a glow wire flammability index ( GWFI ) of 850 ° C and a GWIT of 775 ° C . To determine the GWFI , a hot wire is pressed against a test specimen for 30 seconds . If ignition occurs , the time at which the burning specimen extinguishes after removing the glow wire is measured . Whether burning drops from the specimen ignite a sheet of silk paper underneath the specimen is also tested . Frequently , a material passing UL 94 V-0 also passes GWFI at 850 ° C and at 960 ° C . The test specimen is put in contact with a glow wire for 30 seconds , simulating a defective electric wire .
If the specimen is ignited at 750 ° C ( according to a GWIT classification of 775 ° C ), it should not burn for longer than five seconds . In the UL 94 test , the specimens are ignited by a flame and must be self-extinguishing , in glow wire testing the polymer must not be ignited by a hot wire . Phosphorus FRs ( PFRs ) act mainly in the condensed phase by char formation , which fits well to direct flame tests where self-extinguishing is required . However , the formation of the char needs some seconds of time , which creates a disadvantage to PFRs without necessarily impacting the overall safety level . Brominated FRs ( BFRs ) are active in the gas phase as radical scavengers and are suitable for preventing ignition . Consequently , PAs with BFRs are mainly used for GWITrelevant applications .
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