FLAME RETARDANTS
Dried materials used 230420-1 230420-2 230420-4 PC , Lexan 141R 50 % 40 % 40 % PET , Auriga 7800 30 % 30 % 30 % Nofia HM7000 20 % 20 % 20 % Lotader AX8900 10 % Paraloid EXL-2690 10 %
Total 100 % 100 % 100 %
Compounding temp . C , from feed to die
200 / 275 / 275 / 270 / 265 / 260 / 260 / 260
Dried materials used |
180731-7 |
230327-1 |
230327-3 |
230327-4 |
230327-5 |
PC , Lexan 141R |
66.70 % |
45 % |
35 % |
35 % |
35 % |
PBT , Ultradur B 4520 , BASF |
33 % |
30 % |
30 % |
30 % |
30 % |
Nofia HM7000 |
|
25 % |
25 % |
25 % |
25 % |
Metablen S 2130 |
|
|
10 % |
|
|
Lotader AX8900 |
|
|
|
10 % |
|
Paraloid EXL-2690 |
|
|
|
|
10 % |
PTFE , Teflon 6C |
0.30 % |
|
|
|
|
NI at 3.2mm , J / m 60 870 760
Compounding temp . C , from feed to die
200 / 235 / 235 / 235 / 230 / 230 / 225 / 225
UL-94 at 1.6mm |
V-2 |
V-1 |
V-0 |
t max , sec |
2 |
19 |
8 |
t total , sec |
19 |
48 |
32 |
# Drip / flaming drips |
1 / 1 |
0 / 0 |
0 / 0 |
UL-94 at 0.8mm |
V-2 |
V-1 |
V-0 |
t max , sec |
2 |
12 |
9 |
t total , sec |
13 |
41 |
48 |
# Drip / flaming drips |
13 / 6 |
0 / 0 |
1 / 0 |
Torque at 100 rpm , 10 kg / hr 79 % 58 % 57 % 46 % 58 %
Notched Izod at 3.2mm , J / m NA 60 730 685 635
UL-94 at 1.6mm Not Rated V-2 V-1 V-0 V-0
t max , sec burnt up to clamp
1 20 5 9
t total , sec 10 100 18 26 # Drip / flaming drips 16 / 3 2 / 0 0 / 0 0 / 0
UL-94 at 0.8mm V-0 V-1
Figure 4 - Application of HM70HM00 in PFAS-free FR PC-PBT blend ( a ) & PFAS-free FR PC-ET blend ( b ) for V-0 at 1.6mm & 0.8mm t max , sec 7 15 t total , sec 30 73
# Drip / flaming drips 0 / 0 0 / 0 way . Similar considerations are being applied . We are examining both impact modifiers and other additives , such as stabilisers or chain extenders . They would be most beneficial to FR performance and mechanical properties if they also promote the compatibility between the ingredients in the blend .
PTFE has been a very efficient anti-dripping agent for FR PC and its blends . As low as 0.1-0.3 % loading could prevent dripping and improve the FR performance dramatically by its fibrillary formation . A one-for-one replacement for PTFE would be quite challenging , however .
Some researchers are looking into replacement materials that can be exfoliated at nano-scale in polymer melts , such as nanoclay and carbon nanotubes . Although the nanostructure when formed could prevent dripping , it does not necessarily provide other FR mechanisms provided by PTFE , such as effective char formation . More FRs would therefore need to be added to achieve the same FR performance .
The fatal flaws of adding increasingly higher loadings of small molecule FRs are increased migration of FR to the surface , worse mechanical properties and continued reduction in melt strength and thermal properties . Polymeric FRs like polyphosphonates allow a much bigger formulation space to optimise for FR and mechanical properties without such negative effects .
The examples showcased so far in this article are for demonstration purposes and are in no way optimised . For example , FR synergists can be further introduced into Nofia FR only formulations to reduce the total FR loading and cost .
In PC & PC blends – KPFBS-free
In KPFBS-free formulations , PTFE is still allowed . This makes the use of polyphosphonates much more efficient in FR PC and PC blends . In pigmented FR PC with PTFE , 2 % Nofia CO6010-EX can provide robust V-0 at 1.6mm . When used together with phosphazene , about 10 % CO6010-EX and 1 % phosphazene with PTFE can achieve V-0 at 0.8mm .
In 40 % glass-filled PC with PTFE , 1 % phosphorus from the combination of Nofia HM1100 and bisphenol-A bis ( diphenyl phosphate ) ( BDP ) could achieve V-0 at 0.8mm ( about 5 % Nofia HM1100 / 5 % BDP ). In FR PC / ABS , for a formulation where about 7 % of BDP is needed to achieve V-0 at 1.6mm , 8 % Nofia CO6010-EX was reportedly found to achieve the same FR , but with much higher impact properties and HDT . This has been universally observed when polyphosphonate FRs are used in comparison to the traditional small molecular FRs . ●
* - Nofia is a registered trademark of FRX Polymers . Joncryl and Paraloid are registered trademarks of BASF ; Metablen is a registered trademark of Mitsubishi Chemical ; Lotader is a registered trademark of SK Functional Polymers
J j
Dr Xiudong Sun ,
VICE PRESIDENT , RESEARCH & APPLICATIONS
FRX POLYMERS , INC . xsun @ frxpolymers . com www . frxpolymers . com
60 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981